{"id":108,"date":"2024-08-21T12:02:52","date_gmt":"2024-08-21T12:02:52","guid":{"rendered":"http:\/\/localhost\/researchmethods\/?post_type=content&#038;p=108"},"modified":"2026-08-26T11:38:45","modified_gmt":"2026-08-26T11:38:45","slug":"chapter-16-significance-testing-was-it-a-real-effect","status":"publish","type":"content","link":"https:\/\/routledgelearning.com\/researchmethods\/student-resources\/chapter-16-significance-testing-was-it-a-real-effect\/","title":{"rendered":"Chapter 16 &#8211; Significance testing \u2013 was it a real effect?"},"content":{"rendered":"\n<div class=\"wp-block-group has-base-background-color has-background has-global-padding is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:0;margin-bottom:0;padding-top:var(--wp--preset--spacing--70);padding-bottom:var(--wp--preset--spacing--70)\">\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\"><nav style=\"--separator: &quot;\/&quot;\" class=\"wp-block-breadcrumbs\" aria-label=\"Breadcrumbs\"><ol><li><a href=\"https:\/\/routledgelearning.com\/researchmethods\/\">Home<\/a><\/li><li><a href=\"https:\/\/routledgelearning.com\/researchmethods\/student-resources\/\">Student Resources<\/a><\/li><li><span aria-current=\"page\">Chapter 16 &#8211; Significance testing \u2013 was it a real effect?<\/span><\/li><\/ol><\/nav>\n\n<h1 class=\"alignwide wp-block-post-title has-large-font-size\">Chapter 16 &#8211; Significance testing \u2013 was it a real effect?<\/h1>\n\n\n<p class=\"wp-block-paragraph\">This chapter is about the principles of significance testing.&nbsp;<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-group has-global-padding is-layout-constrained wp-block-group-is-layout-constrained\" style=\"margin-top:0;margin-bottom:0;padding-top:var(--wp--preset--spacing--60);padding-bottom:var(--wp--preset--spacing--60)\">\n<div class=\"wp-block-columns alignwide is-layout-flex wp-container-core-columns-is-layout-7387b849 wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:75%\">\n<h2 id=\"aioseo-exercises\" class=\"wp-block-heading\">Exercises<\/h2>\n\n\n\n<h3 id=\"aioseo-exercise-16-1\" class=\"wp-block-heading\">Exercise 16.1<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>One- or two-tailed tests<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In each case below decide whether the research prediction permits a one-tailed test or whether a two-tailed test is obligatory.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">1.There will be a difference between imagery and rehearsal recall scores.<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">Two-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of the difference was not predicted.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">2. Self-confidence will correlate with self-esteem<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">Two-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of the correlation was not predicted.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">3.Extroverts will have higher comfort scores than introverts<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">One-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of difference was predicted but please note that in most research a two-tailed test is preferred.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">4. Children on the anti-bullying programme will improve their attitude to bullying compared with the control group<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">One-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of difference was predicted but please note that in most research a two-tailed test is preferred.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">5. Children on the anti-bullying programme will differ from the control group children on empathy<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">Two-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of the difference was not predicted.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">6. Anxiety will correlate negatively with self-esteem<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">One-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Explanation: <\/strong>Direction of correlation was predicted but please note that in most research a two-tailed test is preferred.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">7. Participants before an audience will make more errors than participants alone<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">One-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of difference was predicted but please note that in most research a two-tailed test is preferred.<\/p>\n<\/details>\n\n\n\n<p class=\"wp-block-paragraph\">8. Increased caffeine will produce a difference in reaction times<\/p>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<p class=\"wp-block-paragraph\">Two-tailed<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Explanation: Direction of the difference was not predicted.<\/p>\n<\/details>\n\n\n\n<h3 id=\"aioseo-exercise-16-2\" class=\"wp-block-heading\">Exercise 16.2<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Have a go at this short quiz to test your understanding of significance testing and identify any gaps in your knowledge.<\/p>\n\n\n\n<div class=\"wp-block-group has-base-element-background-color has-background has-global-padding is-layout-constrained wp-container-core-group-is-layout-0910e091 wp-block-group-is-layout-constrained\" style=\"border-width:1px;padding-top:var(--wp--preset--spacing--40);padding-right:var(--wp--preset--spacing--40);padding-bottom:var(--wp--preset--spacing--40);padding-left:var(--wp--preset--spacing--40)\">\n<div class=\"wp-block-group alignwide is-layout-flow wp-block-group-is-layout-flow\"><script>\n                            if (window.qmn_quiz_data === undefined) {\n                                    window.qmn_quiz_data = new Object();\n                            }\n                    <\/script><script>window.qmn_quiz_data[\"14\"] = {\"quiz_id\":\"14\",\"quiz_name\":\"exercise162\",\"disable_answer\":0,\"ajax_show_correct\":0,\"progress_bar\":0,\"contact_info_location\":\"0\",\"qpages\":{\"2\":{\"id\":\"2\",\"quizID\":\"14\",\"pagekey\":\"8pDl9PTF\",\"hide_prevbtn\":\"0\"}},\"skip_validation_time_expire\":0,\"timer_limit_val\":0,\"disable_scroll_next_previous_click\":0,\"disable_scroll_on_result\":0,\"disable_first_page\":\"0\",\"enable_result_after_timer_end\":0,\"enable_quick_result_mc\":0,\"end_quiz_if_wrong\":0,\"form_disable_autofill\":0,\"disable_mathjax\":0,\"enable_quick_correct_answer_info\":\"0\",\"quick_result_correct_answer_text\":\"Correct! You have selected correct answer.\",\"quick_result_wrong_answer_text\":\"Wrong! You have selected wrong answer.\",\"quiz_processing_message\":\"\",\"quiz_limit_choice\":\"Limit of choice is reached.\",\"not_allow_after_expired_time\":0,\"scheduled_time_end\":false,\"prevent_reload\":0,\"limit_email_based_submission\":0,\"total_user_tries\":0,\"is_logged_in\":false,\"pagination\":{\"amount\":1,\"section_comments\":\"\",\"total_questions\":6,\"previous_text\":\"Previous\",\"next_text\":\"Next\",\"start_quiz_survey_text\":\"Start Quiz\",\"submit_quiz_text\":\"Submit\"},\"error_messages\":{\"email_error_text\":\"Not a valid e-mail address!\",\"number_error_text\":\"This field must be a number!\",\"incorrect_error_text\":\"The entered text is not correct!\",\"empty_error_text\":\"Please complete all required fields!\",\"contact_field_required_error_text\":\"Please complete all required fields!\",\"url_error_text\":\"The entered URL is not valid!\",\"minlength_error_text\":\"Required atleast %minlength% characters.\",\"maxlength_error_text\":\"Maximum %maxlength% characters allowed.\",\"recaptcha_error_text\":\"ReCaptcha is missing\",\"phone_error_text\":\"Phone number is invalid\",\"empty_grid_radio_checkbox_text\":\"Please complete all  rows required fields!\",\"empty_audio_text\":\"Please upload audio!\"},\"question_list\":{\"94\":{\"question_id\":\"94\",\"quiz_id\":\"14\",\"question_name\":\"Increasing \\u03b1 will increase the risk of type I errors\",\"answer_array\":\"a:2:{i:0;a:3:{i:0;s:4:\\\"True\\\";i:1;d:0;i:2;i:1;}i:1;a:3:{i:0;s:5:\\\"False\\\";i:1;d:0;i:2;i:0;}}\",\"answer_one\":\"\",\"answer_one_points\":\"0\",\"answer_two\":\"\",\"answer_two_points\":\"0\",\"answer_three\":\"\",\"answer_three_points\":\"0\",\"answer_four\":\"\",\"answer_four_points\":\"0\",\"answer_five\":\"\",\"answer_five_points\":\"0\",\"answer_six\":\"\",\"answer_six_points\":\"0\",\"correct_answer\":\"0\",\"question_answer_info\":\"Alpha is the probability that our result would occur if the <em>null hypothesis<\\\/em> is true. If we accept a probability greater than .05 then it becomes more likely that our results could occur just through random fluctuation and hence it is more likely that we have made a type I error \\u2013 assuming the null hypothesis is false when it isn\\u2019t.\",\"comments\":\"1\",\"hints\":\"\",\"question_order\":\"1\",\"question_type\":\"0\",\"question_type_new\":\"0\",\"question_settings\":\"a:15:{s:8:\\\"required\\\";i:0;s:12:\\\"answerEditor\\\";s:4:\\\"text\\\";s:14:\\\"question_title\\\";s:10:\\\"Question 1\\\";s:14:\\\"featureImageID\\\";s:0:\\\"\\\";s:15:\\\"featureImageSrc\\\";s:0:\\\"\\\";s:11:\\\"matchAnswer\\\";s:6:\\\"random\\\";s:14:\\\"case_sensitive\\\";s:0:\\\"\\\";s:16:\\\"image_size-width\\\";s:0:\\\"\\\";s:17:\\\"image_size-height\\\";s:0:\\\"\\\";s:8:\\\"autofill\\\";s:0:\\\"\\\";s:10:\\\"limit_text\\\";s:1:\\\"0\\\";s:23:\\\"limit_multiple_response\\\";s:1:\\\"0\\\";s:17:\\\"file_upload_limit\\\";s:1:\\\"4\\\";s:16:\\\"file_upload_type\\\";s:21:\\\"image,application\\\/pdf\\\";s:15:\\\"min_text_length\\\";s:0:\\\"\\\";}\",\"category\":\"\",\"linked_question\":\"\",\"deleted\":\"0\",\"deleted_question_bank\":\"0\",\"answers\":[[\"True\",0,1],[\"False\",0,0]]},\"95\":{\"question_id\":\"95\",\"quiz_id\":\"14\",\"question_name\":\"Decreasing \\u03b1 will decrease the risk of type II errors\",\"answer_array\":\"a:2:{i:0;a:3:{i:0;s:4:\\\"True\\\";i:1;d:0;i:2;i:0;}i:1;a:3:{i:0;s:5:\\\"False\\\";i:1;d:0;i:2;i:1;}}\",\"answer_one\":\"\",\"answer_one_points\":\"0\",\"answer_two\":\"\",\"answer_two_points\":\"0\",\"answer_three\":\"\",\"answer_three_points\":\"0\",\"answer_four\":\"\",\"answer_four_points\":\"0\",\"answer_five\":\"\",\"answer_five_points\":\"0\",\"answer_six\":\"\",\"answer_six_points\":\"0\",\"correct_answer\":\"0\",\"question_answer_info\":\"If we decrease alpha it becomes more likely that we will retain the null hypothesis when it is false. Hence we <em>increase<\\\/em> the risk of type II errors.\",\"comments\":\"1\",\"hints\":\"\",\"question_order\":\"1\",\"question_type\":\"0\",\"question_type_new\":\"0\",\"question_settings\":\"a:15:{s:8:\\\"required\\\";i:0;s:12:\\\"answerEditor\\\";s:4:\\\"text\\\";s:14:\\\"question_title\\\";s:10:\\\"Question 2\\\";s:14:\\\"featureImageID\\\";s:0:\\\"\\\";s:15:\\\"featureImageSrc\\\";s:0:\\\"\\\";s:11:\\\"matchAnswer\\\";s:6:\\\"random\\\";s:14:\\\"case_sensitive\\\";s:0:\\\"\\\";s:16:\\\"image_size-width\\\";s:0:\\\"\\\";s:17:\\\"image_size-height\\\";s:0:\\\"\\\";s:8:\\\"autofill\\\";s:0:\\\"\\\";s:10:\\\"limit_text\\\";s:1:\\\"0\\\";s:23:\\\"limit_multiple_response\\\";s:1:\\\"0\\\";s:17:\\\"file_upload_limit\\\";s:1:\\\"4\\\";s:16:\\\"file_upload_type\\\";s:21:\\\"image,application\\\/pdf\\\";s:15:\\\"min_text_length\\\";s:0:\\\"\\\";}\",\"category\":\"\",\"linked_question\":\"\",\"deleted\":\"0\",\"deleted_question_bank\":\"0\",\"answers\":[[\"True\",0,0],[\"False\",0,1]]},\"96\":{\"question_id\":\"96\",\"quiz_id\":\"14\",\"question_name\":\"If the null hypothesis is true a type I error is logically impossible\",\"answer_array\":\"a:2:{i:0;a:3:{i:0;s:4:\\\"True\\\";i:1;d:0;i:2;i:0;}i:1;a:3:{i:0;s:5:\\\"False\\\";i:1;d:0;i:2;i:1;}}\",\"answer_one\":\"\",\"answer_one_points\":\"0\",\"answer_two\":\"\",\"answer_two_points\":\"0\",\"answer_three\":\"\",\"answer_three_points\":\"0\",\"answer_four\":\"\",\"answer_four_points\":\"0\",\"answer_five\":\"\",\"answer_five_points\":\"0\",\"answer_six\":\"\",\"answer_six_points\":\"0\",\"correct_answer\":\"0\",\"question_answer_info\":\"If the null hypothesis is true then most data gathered under it will vary only a little at random. However when the data vary a lot we reject the null hypothesis and sometime when we do this we will be wrong.\",\"comments\":\"1\",\"hints\":\"\",\"question_order\":\"1\",\"question_type\":\"0\",\"question_type_new\":\"0\",\"question_settings\":\"a:15:{s:8:\\\"required\\\";i:0;s:12:\\\"answerEditor\\\";s:4:\\\"text\\\";s:14:\\\"question_title\\\";s:10:\\\"Question 3\\\";s:14:\\\"featureImageID\\\";s:0:\\\"\\\";s:15:\\\"featureImageSrc\\\";s:0:\\\"\\\";s:11:\\\"matchAnswer\\\";s:6:\\\"random\\\";s:14:\\\"case_sensitive\\\";s:0:\\\"\\\";s:16:\\\"image_size-width\\\";s:0:\\\"\\\";s:17:\\\"image_size-height\\\";s:0:\\\"\\\";s:8:\\\"autofill\\\";s:0:\\\"\\\";s:10:\\\"limit_text\\\";s:1:\\\"0\\\";s:23:\\\"limit_multiple_response\\\";s:1:\\\"0\\\";s:17:\\\"file_upload_limit\\\";s:1:\\\"4\\\";s:16:\\\"file_upload_type\\\";s:21:\\\"image,application\\\/pdf\\\";s:15:\\\"min_text_length\\\";s:0:\\\"\\\";}\",\"category\":\"\",\"linked_question\":\"\",\"deleted\":\"0\",\"deleted_question_bank\":\"0\",\"answers\":[[\"True\",0,0],[\"False\",0,1]]},\"97\":{\"question_id\":\"97\",\"quiz_id\":\"14\",\"question_name\":\"If the alternative hypothesis is false a type II error is logically impossible\",\"answer_array\":\"a:2:{i:0;a:3:{i:0;s:4:\\\"True\\\";i:1;d:0;i:2;i:1;}i:1;a:3:{i:0;s:5:\\\"False\\\";i:1;d:0;i:2;i:0;}}\",\"answer_one\":\"\",\"answer_one_points\":\"0\",\"answer_two\":\"\",\"answer_two_points\":\"0\",\"answer_three\":\"\",\"answer_three_points\":\"0\",\"answer_four\":\"\",\"answer_four_points\":\"0\",\"answer_five\":\"\",\"answer_five_points\":\"0\",\"answer_six\":\"\",\"answer_six_points\":\"0\",\"correct_answer\":\"0\",\"question_answer_info\":\"A type II error assumes occurs where we reject the alternative hypothesis when it is true. If it is not true then logically this cannot happen.\",\"comments\":\"1\",\"hints\":\"\",\"question_order\":\"1\",\"question_type\":\"0\",\"question_type_new\":\"0\",\"question_settings\":\"a:15:{s:8:\\\"required\\\";i:0;s:12:\\\"answerEditor\\\";s:4:\\\"text\\\";s:14:\\\"question_title\\\";s:10:\\\"Question 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6\\\";s:14:\\\"featureImageID\\\";s:0:\\\"\\\";s:15:\\\"featureImageSrc\\\";s:0:\\\"\\\";s:11:\\\"matchAnswer\\\";s:6:\\\"random\\\";s:14:\\\"case_sensitive\\\";s:0:\\\"\\\";s:16:\\\"image_size-width\\\";s:0:\\\"\\\";s:17:\\\"image_size-height\\\";s:0:\\\"\\\";s:8:\\\"autofill\\\";s:0:\\\"\\\";s:10:\\\"limit_text\\\";s:1:\\\"0\\\";s:23:\\\"limit_multiple_response\\\";s:1:\\\"0\\\";s:17:\\\"file_upload_limit\\\";s:1:\\\"4\\\";s:16:\\\"file_upload_type\\\";s:21:\\\"image,application\\\/pdf\\\";s:15:\\\"min_text_length\\\";s:0:\\\"\\\";}\",\"category\":\"\",\"linked_question\":\"\",\"deleted\":\"0\",\"deleted_question_bank\":\"0\",\"answers\":[[\"True\",0,0],[\"False\",0,1]]}},\"first_page\":false,\"questions_settings\":[]}\n                    <\/script>\t\t<div class='qsm-quiz-container qsm-quiz-container-14 qmn_quiz_container mlw_qmn_quiz qsm_auto_pagination_enabled quiz_theme_default  '>\n\t\t\t\t\t\t\t\t<form name=\"quizForm14\" id=\"quizForm14\" action=\"\/researchmethods\/wp-json\/wp\/v2\/content\/108\/\" method=\"POST\" class=\"qsm-quiz-form qmn_quiz_form mlw_quiz_form\" novalidate enctype=\"multipart\/form-data\">\n\t\t\t\t<input type=\"hidden\" name=\"qsm_hidden_questions\" id=\"qsm_hidden_questions\" value=\"\">\n\t\t\t\t<input type=\"hidden\" name=\"qsm_nonce\" id=\"qsm_nonce_14\" value=\"a04a95fea6\">\n\t\t\t\t<input type=\"hidden\" name=\"qsm_unique_key\" id=\"qsm_unique_key_14\" value=\"6a8f986e446da\">\n\t\t\t\t<div id=\"mlw_error_message\" class=\"qsm-error-message qmn_error_message_section\"><\/div>\n\t\t\t\t<span id=\"mlw_top_of_quiz\"><\/span>\n\t\t\t\t\t\t\t\t\t<div class=\"qsm-auto-page-row qsm-question-page qsm-apc-1\" data-apid=\"1\" data-qpid=\"1\" style=\"display: none;\">\n\t\t\t\t\t\t\t\t<div class=\"quiz_section qsm-question-wrapper question-type-0  question-section-id-94 slide0 \">\n\t\t\t\t\t\t<div class='mlw_qmn_new_question'>Question 1 <\/div>\n\t\t\t<div class='mlw_qmn_question  qsm_remove_bold' >\n\t\t<p>Increasing \u03b1 will increase the risk of type I errors<\/p>\n\t<\/div>\n\t\t<fieldset>\n\t\t<legend><\/legend>\n\t<div class='qmn_radio_answers mlwRequiredRadio'>\n\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question94-1 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question94\" id=\"question94_1\" value=\"0\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question94_1\">\n\t\t\t\t\tTrue\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question94-2 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question94\" id=\"question94_2\" value=\"1\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question94_2\">\n\t\t\t\t\tFalse\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t \t\t\t<label style=\"display: none !important;\" for=\"question94_none\">None<\/label>\n\t\t\t<input type=\"radio\" style=\"display: none;\" name=\"question94\" id=\"question94_none\" checked=\"checked\" value=\"\" \/>\n\t\t\t\t<\/div>\n\t<\/fieldset>\n\t<input type=\"hidden\" name=\"answer_limit_keys_94\" value=\"\" \/>\n\t\t\t\t<\/div><!-- .quiz_section -->\n\t\t\t\t\t\t\t\t<\/div><!-- .qsm-auto-page-row -->\n\t\t\t\t\t\t\t\t\t\t<div class=\"qsm-auto-page-row qsm-question-page qsm-apc-2\" data-apid=\"2\" data-qpid=\"2\" style=\"display: none;\">\n\t\t\t\t\t\t\t\t<div class=\"quiz_section qsm-question-wrapper question-type-0  question-section-id-95 slide1 \">\n\t\t\t\t\t\t<div class='mlw_qmn_new_question'>Question 2 <\/div>\n\t\t\t<div class='mlw_qmn_question  qsm_remove_bold' >\n\t\t<p>Decreasing \u03b1 will decrease the risk of type II errors<\/p>\n\t<\/div>\n\t\t<fieldset>\n\t\t<legend><\/legend>\n\t<div class='qmn_radio_answers mlwRequiredRadio'>\n\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question95-1 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question95\" id=\"question95_1\" value=\"0\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question95_1\">\n\t\t\t\t\tTrue\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question95-2 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question95\" id=\"question95_2\" value=\"1\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question95_2\">\n\t\t\t\t\tFalse\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t \t\t\t<label style=\"display: none !important;\" for=\"question95_none\">None<\/label>\n\t\t\t<input type=\"radio\" style=\"display: none;\" name=\"question95\" id=\"question95_none\" checked=\"checked\" value=\"\" \/>\n\t\t\t\t<\/div>\n\t<\/fieldset>\n\t<input type=\"hidden\" name=\"answer_limit_keys_95\" value=\"\" \/>\n\t\t\t\t<\/div><!-- .quiz_section -->\n\t\t\t\t\t\t\t\t<\/div><!-- .qsm-auto-page-row -->\n\t\t\t\t\t\t\t\t\t\t<div class=\"qsm-auto-page-row qsm-question-page qsm-apc-3\" data-apid=\"3\" data-qpid=\"3\" style=\"display: none;\">\n\t\t\t\t\t\t\t\t<div class=\"quiz_section qsm-question-wrapper question-type-0  question-section-id-96 slide2 \">\n\t\t\t\t\t\t<div class='mlw_qmn_new_question'>Question 3 <\/div>\n\t\t\t<div class='mlw_qmn_question  qsm_remove_bold' >\n\t\t<p>If the null hypothesis is true a type I error is logically impossible<\/p>\n\t<\/div>\n\t\t<fieldset>\n\t\t<legend><\/legend>\n\t<div class='qmn_radio_answers mlwRequiredRadio'>\n\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question96-1 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question96\" id=\"question96_1\" value=\"0\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question96_1\">\n\t\t\t\t\tTrue\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question96-2 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question96\" id=\"question96_2\" value=\"1\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question96_2\">\n\t\t\t\t\tFalse\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t \t\t\t<label style=\"display: none !important;\" for=\"question96_none\">None<\/label>\n\t\t\t<input type=\"radio\" style=\"display: none;\" name=\"question96\" id=\"question96_none\" checked=\"checked\" value=\"\" \/>\n\t\t\t\t<\/div>\n\t<\/fieldset>\n\t<input type=\"hidden\" name=\"answer_limit_keys_96\" value=\"\" \/>\n\t\t\t\t<\/div><!-- .quiz_section -->\n\t\t\t\t\t\t\t\t<\/div><!-- .qsm-auto-page-row -->\n\t\t\t\t\t\t\t\t\t\t<div class=\"qsm-auto-page-row qsm-question-page qsm-apc-4\" data-apid=\"4\" data-qpid=\"4\" style=\"display: none;\">\n\t\t\t\t\t\t\t\t<div class=\"quiz_section qsm-question-wrapper question-type-0  question-section-id-97 slide3 \">\n\t\t\t\t\t\t<div class='mlw_qmn_new_question'>Question 4 <\/div>\n\t\t\t<div class='mlw_qmn_question  qsm_remove_bold' >\n\t\t<p>If the alternative hypothesis is false a type II error is logically impossible<\/p>\n\t<\/div>\n\t\t<fieldset>\n\t\t<legend><\/legend>\n\t<div class='qmn_radio_answers mlwRequiredRadio'>\n\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question97-1 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question97\" id=\"question97_1\" value=\"0\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question97_1\">\n\t\t\t\t\tTrue\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question97-2 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question97\" id=\"question97_2\" value=\"1\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question97_2\">\n\t\t\t\t\tFalse\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t \t\t\t<label style=\"display: none !important;\" for=\"question97_none\">None<\/label>\n\t\t\t<input type=\"radio\" style=\"display: none;\" name=\"question97\" id=\"question97_none\" checked=\"checked\" value=\"\" \/>\n\t\t\t\t<\/div>\n\t<\/fieldset>\n\t<input type=\"hidden\" name=\"answer_limit_keys_97\" value=\"\" \/>\n\t\t\t\t<\/div><!-- .quiz_section -->\n\t\t\t\t\t\t\t\t<\/div><!-- .qsm-auto-page-row -->\n\t\t\t\t\t\t\t\t\t\t<div class=\"qsm-auto-page-row qsm-question-page qsm-apc-5\" data-apid=\"5\" data-qpid=\"5\" style=\"display: none;\">\n\t\t\t\t\t\t\t\t<div class=\"quiz_section qsm-question-wrapper question-type-0  question-section-id-98 slide4 \">\n\t\t\t\t\t\t<div class='mlw_qmn_new_question'>Question 5 <\/div>\n\t\t\t<div class='mlw_qmn_question  qsm_remove_bold' >\n\t\t<p>\u03b2 is the probability of making a type II error<\/p>\n\t<\/div>\n\t\t<fieldset>\n\t\t<legend><\/legend>\n\t<div class='qmn_radio_answers mlwRequiredRadio'>\n\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question98-1 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question98\" id=\"question98_1\" value=\"0\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question98_1\">\n\t\t\t\t\tTrue\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question98-2 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question98\" id=\"question98_2\" value=\"1\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question98_2\">\n\t\t\t\t\tFalse\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t \t\t\t<label style=\"display: none !important;\" for=\"question98_none\">None<\/label>\n\t\t\t<input type=\"radio\" style=\"display: none;\" name=\"question98\" id=\"question98_none\" checked=\"checked\" value=\"\" \/>\n\t\t\t\t<\/div>\n\t<\/fieldset>\n\t<input type=\"hidden\" name=\"answer_limit_keys_98\" value=\"\" \/>\n\t\t\t\t<\/div><!-- .quiz_section -->\n\t\t\t\t\t\t\t\t<\/div><!-- .qsm-auto-page-row -->\n\t\t\t\t\t\t\t\t\t\t<div class=\"qsm-auto-page-row qsm-question-page qsm-apc-6\" data-apid=\"6\" data-qpid=\"6\" style=\"display: none;\">\n\t\t\t\t\t\t\t\t<div class=\"quiz_section qsm-question-wrapper question-type-0  question-section-id-99 slide5 \">\n\t\t\t\t\t\t<div class='mlw_qmn_new_question'>Question 6 <\/div>\n\t\t\t<div class='mlw_qmn_question  qsm_remove_bold' >\n\t\t<p>1 &#8211; \u03b2 is the probability of making a type II error<\/p>\n\t<\/div>\n\t\t<fieldset>\n\t\t<legend><\/legend>\n\t<div class='qmn_radio_answers mlwRequiredRadio'>\n\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question99-1 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question99\" id=\"question99_1\" value=\"0\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question99_1\">\n\t\t\t\t\tTrue\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<div class=\"qmn_mc_answer_wrap  mrq_checkbox_class\" id=\"question99-2 \">\n\t\t\t\t\t\t\t\t\t\t\t<input type='radio' class='qmn_quiz_radio qmn-multiple-choice-input ' name=\"question99\" id=\"question99_2\" value=\"1\" \/>\n\t\t\t\t\t<label class=\"qsm-input-label\" for=\"question99_2\">\n\t\t\t\t\tFalse\t\t\t\t\t<\/label>\n\t\t\t\t\t \t\t\t\t<\/div>\n\t\t\t\t\t \t\t\t<label style=\"display: none !important;\" for=\"question99_none\">None<\/label>\n\t\t\t<input type=\"radio\" style=\"display: none;\" name=\"question99\" id=\"question99_none\" checked=\"checked\" value=\"\" \/>\n\t\t\t\t<\/div>\n\t<\/fieldset>\n\t<input type=\"hidden\" name=\"answer_limit_keys_99\" value=\"\" \/>\n\t\t\t\t<\/div><!-- .quiz_section -->\n\t\t\t\t\t\t\t\t<\/div><!-- .qsm-auto-page-row -->\n\t\t\t\t\t\t\t<input type=\"hidden\" name=\"qmn_question_list\" value=\"94Q95Q96Q97Q98Q99Q\" \/>\n\t\t\t\t\t<div class=\"qsm-auto-page-row quiz_section quiz_end empty_quiz_end qsm-d-none\" >\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<div id=\"mlw_error_message_bottom\" class=\"qsm-error-message qmn_error_message_section\"><\/div>\n\t\t\t\t\t<input type=\"hidden\" name=\"qmn_all_questions_count\" id=\"qmn_all_questions_count\" value=\"6\" \/>\n\t\t\t\t\t<input type=\"hidden\" name=\"total_questions\" id=\"total_questions\" value=\"6\" \/>\n\t\t\t\t\t<input type=\"hidden\" name=\"timer\" id=\"timer\" value=\"0\" \/>\n\t\t\t\t\t<input type=\"hidden\" name=\"timer_ms\" id=\"timer_ms\" value=\"0\"\/>\n\t\t\t\t\t<input type=\"hidden\" class=\"qmn_quiz_id\" name=\"qmn_quiz_id\" id=\"qmn_quiz_id\" value=\"14\" \/>\n\t\t\t\t\t<input type='hidden' name='complete_quiz' value='confirmation' \/>\n\t\t\t\t\t\t\t\t\t<\/form>\n\t\t\t\t\t\t<\/div>\n\t\t<div style=\"display: none;\" class=\"qsm-popup qsm-popup-slide\" id=\"modal-4\" aria-hidden=\"false\"><div class=\"qsm-popup__overlay\" tabindex=\"-1\" data-micromodal-close=\"\"><div class=\"qsm-popup__container qmn_quiz_container\" role=\"dialog\" aria-modal=\"true\"><div class=\"qsm-popup__content\"><img decoding=\"async\" src=\"https:\/\/routledgelearning.com\/researchmethods\/wp-content\/plugins\/quiz-master-next\/assets\/clock.png\" alt=\"clock.png\"\/><p class=\"qsm-time-up-text\"> Time&#8217;s up<\/p><\/div><footer class=\"qsm-popup__footer\"><button class=\"qsm-popup-secondary-button qmn_btn\" data-micromodal-close=\"\" aria-label=\"Close this dialog window\" onclick=\"location.reload();\">Cancel<\/button><\/footer><\/div><\/div><\/div><\/div>\n<\/div>\n\n\n\n<h3 id=\"aioseo-exercise-16-3\" class=\"wp-block-heading\">Exercise 16.3<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><em>z<\/em> values and significance<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In the chapter we looked at a value of <em>z<\/em> and found the probability that a <em>z <\/em>that high or higher would be produced at random under the null hypothesis. We do that by taking the probability remaining to the right of the <em>z<\/em> value on the normal distribution in Appendix table 2 (if the <em>z<\/em> is negative we look at the other tail as in a mirror). Following this process, in the table below enter the exact value of <em>p<\/em> that you find from Appendix table 2. Don\u2019t forget that with a two-tailed test we use the probabilities at both ends of the distribution. That is we just double the value found for one end<em>. <\/em>Enter your value with a decimal point and four decimal places exactly as in the table. Decide whether a <em>z<\/em> of this value would be declared significant with <em>p<\/em> \u2264 .05<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>&nbsp;<\/td><td><em>z&nbsp;<\/em>value<\/td><td>One or Two tailed<\/td><td><em>p<\/em>&nbsp;=<\/td><td>Significant?<\/td><\/tr><tr><td>a<\/td><td>0.78<\/td><td>One<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><tr><td>b<\/td><td>1.97<\/td><td>Two<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><tr><td>c<\/td><td>2.56<\/td><td>Two<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><tr><td>d<\/td><td>-2.24<\/td><td>Two<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><tr><td>e<\/td><td>1.56<\/td><td>One<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><tr><td>f<\/td><td>-1.82<\/td><td>Two<\/td><td>&nbsp;<\/td><td>&nbsp;<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Show answer<\/summary>\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>&nbsp;<\/td><td><em>z&nbsp;<\/em>value<\/td><td>One or Two tailed<\/td><td><em>p<\/em>&nbsp;=<\/td><td>Significant?<\/td><td>Feedback<\/td><\/tr><tr><td>a<\/td><td>0.78<\/td><td>One<\/td><td>.2177<\/td><td>No<\/td><td>.2177 is not less than .05 as it needs to be for significance<\/td><\/tr><tr><td>b<\/td><td>1.97<\/td><td>Two<\/td><td>.0488<\/td><td>Yes<\/td><td>.0488 just gets under .05<\/td><\/tr><tr><td>c<\/td><td>2.56<\/td><td>Two<\/td><td>.0104<\/td><td>Yes<\/td><td>.0104 is lower than .05<\/td><\/tr><tr><td>d<\/td><td>-2.24<\/td><td>Two<\/td><td>.0250<\/td><td>Yes<\/td><td>.025 is lower than .05<\/td><\/tr><tr><td>e<\/td><td>1.56<\/td><td>One<\/td><td>.0594<\/td><td>No<\/td><td>.0594 is higher than .05<\/td><\/tr><tr><td>f<\/td><td>-1.82<\/td><td>Two<\/td><td>.0688<\/td><td>No<\/td><td>.0688 is higher than .05<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/details>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 id=\"aioseo-weblinks\" class=\"wp-block-heading\">Weblinks<\/h2>\n\n\n\n<h3 id=\"aioseo-significance-testing-was-it-a-real-effect-weblinks\" class=\"wp-block-heading\">Significance testing&nbsp; &#8211; was it a real effect?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A YouTube video with simple explanation of <a><\/a><em>p<\/em> values, Type I error, effect size and statistical vs. practical significance.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.youtube.com\/watch?v=W_bWzoFkGWc\">What Statistical Significance Means \u2013 Part 1 (8-11) &#8211; YouTube<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">See the relationship between power, sample size, Type I and Type II error by sliding these values on a normal distribution.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/rpsychologist.com\/d3\/nhst\">https:\/\/rpsychologist.com\/d3\/nhst<\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">An article by Masicampo and Lalande (2012) showing that a larger than expected number of findings are reported as significant at just under the 0.05 level.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.bps.org.uk\/research-digest\/made-it-uncanny-number-psychology-findings-manage-scrape-statistical-significance\">https:\/\/www.bps.org.uk\/research-digest\/made-it-uncanny-number-psychology-findings-manage-scrape-statistical-significance<\/a><\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 id=\"aioseo-further-information\" class=\"wp-block-heading\">Further Information<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Sod\u2019s law \u2013 or Murphy\u2019s law as the Americans more delicately put it<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A discussion of Sod\u2019s law \u2013 a BBC spoof documentary about testing the notion that toast always falls butter side down and other issues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Do you ever get the feeling that fate has it in for you? At the supermarket, for instance, do you always pick the wrong queue, the one looking shorter but which contains someone with 5 un-priced items and several redemption coupons or with the checkout clerk about to take a tea break? Do you take the outside lane only to find there\u2019s a hidden right-turner? Sod\u2019s law (known as Murphy\u2019s law in the US), in its simplest form states that whatever can go wrong, will. Have you ever returned an item to a shop, or taken a car to the garage with a problem, only to find it working perfectly for the assistant? This is Sod\u2019s law working in reverse but still against you. A colleague of mine holds the extension of Sod\u2019s law that things will go wrong even if they can\u2019t. An amusing QED (BBC) TV programme (Murphy\u2019s Law, 1991<a href=\"#_ftn1\" id=\"_ftnref1\">[1]<\/a>) tested this perspective of subjective probability. The particular hypothesis, following from the law, was that celebrated kitchen occurrence where toast always falls butter side down \u2013 doesn\u2019t it? First attempts engaged a university physics professor in developing machines for tossing the toast without bias. These included modified toasters and an electric typewriter. Results from this were not encouraging. The null hypothesis doggedly retained itself, buttered sides not making significantly more contact with the floor than unbuttered sides. It was decided that the human element was missing. Sod\u2019s law might only work for human toast droppers.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The attempt at more naturalistic simulation was made using students and a stately home now belonging to the University of Newcastle. Benches and tables were laid out in the grounds and dozens of students asked to butter one side of bread then throw it in a specially trained fashion to avoid toss bias. In a cunning variation of the experiment, a new independent variable was introduced. Students were asked to pull out their slice of bread and, just before they were about to butter a side, to change their decision and butter the other side instead. This should produce a bias away from butter on grass if sides to fall on the floor are decided by fate early on in the buttering process. Sadly neither this nor the first experiment produced verification of Sod\u2019s law. In both cases 148 slices fell one way and 152 the other \u2013 first in favour of Murphy\u2019s law then against it. Now the scientists had one of those flashes of creative insight. A corollary of Sod\u2019s law is that when things go wrong (as they surely will \u2013 general rule) they will go wrong in the worst possible manner. The researchers now placed expensive carpet over the lawn. Surely this would tempt fate into a reaction? Do things fall butter side down more often on the living room carpet (I\u2019m sure they do!)? I\u2019m afraid this was the extent of the research. Frequencies were yet again at chance level, 146 buttered side down, 154 up.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Murphy, it turned out, was a United States services officer testing for space flight by sending service men on a horizontally jet propelled chair across a mid-Western desert to produce many Gs of gravitational pressure. I\u2019m still not convinced about his law. Psychologists suggest the explanation might lie in selective memory \u2013 we tend to remember the annoying incidents and ignore all the un-notable dry sides down or whizzes through the supermarket tills. But I still see looks on customers\u2019 faces as they wait patiently \u2013 they seem to know something about my queue \u2026<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>The sociologist\u2019s chip shop<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">An attempt to exemplify the concepts of the null hypothesis and significance in an everyday homely tale of chips.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Imagine one lunchtime you visit the local fish and chip emporium near the college and get into conversation with the chippy. At one point she asks you: \u2018You\u2019re from the college then? What do you study?\u2019. Upon your reply she makes a rasping sound in her throat and snaps back. \u2018Psychology?!!! Yeughhh!!!&nbsp; All that individualist, positivistic crap, unethical manipulation of human beings, nonsensical reductionism rendering continuous human action into pseudo-scientific behavioural elements. What a load of old cobblers! Give me sociology any day. Post-Marxist-Leninist socialism, symbolic interactionism, real life qualitative participative research and a good dollop of post-modern deconstructionism\u2019. You begin to suspect she may not be entirely fond of psychology as an academic subject. You meekly take your bag of chips and proceed outside only to find that your bag contains far too many short chips, whilst your sociology friends all have healthy long ones.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">We must at this point stretch fantasy a little further by assuming that this story is set in an age where, post-salmonella, BSE and genetically modified food, short chips are the latest health scare; long chips are seen as far healthier since they contain less fat overall (thanks to my students for this idea).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Being a well-trained, empirically based psychology student, you decide to design a test of the general theory that the chippy is biased in serving chips to psychology and sociology students. You engage the help of a pair of identical twins and send them simultaneously, identically clothed, into the chip shop to purchase a single bag of chips. One twin wears a large badge saying \u2018I like psychology\u2019 whilst the other twin wears an identical badge, apart from the replacement of \u2018psychology\u2019 with \u2018sociology\u2019. (OK! OK! I spotted the problem too! Which twin should go first? Those bothered about this can devise some sort of counterbalanced design \u2013 see Chapter 3 \u2013 but for now I really don\u2019t want to distract from the point of this example). Just as you had suspected, without a word being spoken by the twins beyond their simple request, the sociology twin has far longer chips in her bag than does the psychology twin!<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Now, we only have the two samples of chips to work with. We cannot see what goes on behind the chippy\u2019s stainless steel counter. We have to entertain two possibilities. Either the chippy drew the two samples (fairly) from one big chip bin (H0) or the bags were filled from two separate chip bins, one with smaller chips overall and therefore with a smaller mean chip length than the other bin (H1). You now need to do some calculations to estimate the probability of getting such a large difference between samples if the bags were filled from the same bin (i.e., if the null hypothesis is true). If the probability is very low you might march back into the shop and demand redress (hence you have rejected H0!). If the probability is quite high \u2013 two bags from the same bin are often this different \u2013 you do not have a case. You must retain the null hypothesis.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In this example, our research prediction would be that the sociology student will receive longer chips than the psychology student. Our alternative hypothesis is that the psychology and sociology chip population means are different; the null hypothesis that the population means are the same (i.e., the samples were drawn from the same population).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Please, sir, may we use a one-tailed test, sir?<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A discussion of the arguments for and against the use of one-tailed tests in statistical analysis in psychology.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">It is hard to imagine statisticians having a heated and passionate debate about their subject matter. However, they\u2019re scientists and of course they do. Odd, though, are the sorts of things they fall out over. Whether it is legitimate to do one-tailed tests in psychology on directional hypotheses is, believe it or not, one of these issues. Here are some views against the use of one-tailed tests on two-group psychological data.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A directional test requires that no rationale at all should exist for any systematic difference in the opposite direction, so there are very few situations indeed where a directional test is appropriate with psychological data consisting of two sets of scores.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">MacRae, 1995<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">I recommend using a non-directional test to compare any two groups of scores \u2026 Questions about directional tests should never be asked in A level examinations.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">MacRae, 1995<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">I say always do two-tailed tests and if you are worried about b, jack the sample size up a bit to offset the loss in power.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Bradley, 1983 (Cited in Howell, 1992)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">And some arguments for the use of one-tailed tests are as follows:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">To generate a theory about how the world works that implies an expected direction of an effect, but then to hedge one\u2019s bet by putting some (up to 1\u20442) of the rejection region in the tail other than that predicted by the theory,&nbsp; strikes me as both scientifically dumb and slightly unethical \u2026 Theory generation and theory testing are much closer to the proper goal of science than truth searching, and running one-tailed tests is quite consistent with those goals.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Rodgers, 1986 (cited in Howell, 1992)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u2026 it has been argued that there are few, if any, instances where the direction [of differences] is not of interest. At any rate, it is the opinion of this writer that directional tests should be used more frequently.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ferguson and Takane, 1989<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">MacRae is saying that when we conduct a one-tailed test, any result in the non-predicted direction would have to be seen as a chance outcome since the null hypothesis for directional tests covers all that the alternative hypothesis does not. If the alternative hypothesis says the population mean is larger than 40 (say) then the null hypothesis is that the population mean is 40 or less. To justify use of a one-tailed test, you must, in a sense, be honestly and entirely uninterested in an effect in the opposite direction. A textbook example (one taken from a pure statistics book, not a statistics-for-social-science textbook) would be where a government agency is checking on a company to see that it meets its claim to include a minimum amount of (costly) vitamin X in its product. It predicts and tests for variations below the minimum. Variations above are not of interest and almost certainly are relatively small and rare, given the industry\u2019s economic interests. A possibly equivalent psychological example could be where a therapist deals with severely depressed patients who score very much up the top end of a depression scale. As a result of therapy a decline in depression is predicted. Variations towards greater depression are almost meaningless since, after a measurement of serious depression, the idea of becoming even more depressed is unmeasurable and perhaps unobservable.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Rodgers, however, says what most people feel when they conduct psychological projects. Why on earth should I check the other way when the theory and past research so clearly point in this one direction? In a sense, all MacRae and Bradley are asking is that we operate with greater surety and always use the 2.5% level rather than the 5% level. If we\u2019ve predicted a result, from closely argued theory, that goes in one direction, then use two-tailed values and find we are significant in the opposite direction, we\u2019re hardly likely to jump about saying \u2018Eureka! It\u2019s not what I wanted but it\u2019s significant!\u2019 Probably we will still walk away glumly, as for a failure to reach significance, saying \u2018What went wrong then?\u2019 It will still feel like \u2018failure\u2019. If we had a point to make we haven\u2019t made it, so we\u2019re hardly likely to rush off to publish now. Our theoretical argument, producing our hypothesis, would look silly (though it may be possible to attempt an explanation of the unexpected result).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">During this argument it always strikes me as bizarre that textbooks talk as if researchers really do stick rigidly to a hypothesis testing order: think through theory, make a specific prediction, set alpha, decide on one- or two-tailed test, find out what the probability is, make significance decision. The real order of events is a whole lot more disjointed than that. During research, many results are inspected and jiggled with. Participants are added to increase N. Some results are simply discarded.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Researchers usually know what all the probability values are, however, before they come to tackle the niggling problem of whether it would be advisable to offer a one- or two-tailed analysis in their proposed research article. When the one-tailed test decision is made is a rather arbitrary matter. In some circles and at some times it depends on the received view of what is correct. In others it depends on the actual theory (as it should) and in others it will depend on who, specifically, is on the panel reviewing submitted articles.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">So what would happen, realistically speaking, if a researcher or research team obtained an opposite but highly \u2018significant\u2019 result, having made a directional prediction? In reality I\u2019m sure that if such a reversal did in fact occur, the research team would sit back and say \u2018Hmm! That\u2019s interesting!\u2019 They\u2019re not likely to walk away from such an apparently strong effect, even though it initially contradicts their theorising. The early research on social facilitation was littered with results that went first one way (audiences make you perform better) then the other (no, they don\u2019t; they make performance worse). Theories and research findings rarely follow the pure and simple ideal. It is rare in psychology for a researcher to find one contrary result and say \u2018Oh well. That blows my whole theory apart. Back to the drawing board. What shall I turn my hand to today then?\u2019 The result would slot into a whole range of findings and a research team with this dilemma might start to re-assess their method, look at possible confounding variables in their design and even consider some re-organisation of their theory in order to incorporate the effect.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">It is important to recognise the usefulness of this kind of result. Far from leaving the opposite direction result as a \u2018chance event\u2019, the greater likelihood is that this finding will be investigated further. A replication of the effect, using a large enough sample to get p \u2264 .01, would be of enormous interest if it clearly contradicts theoretical predictions \u2013 see what the book says about the 1% level.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">So should you do one-tailed tests? This is clearly not a question I\u2019m going to answer, since it really does depend upon so many things and is clearly an issue over which the experts can lose friends. I can only ever recall one research article that used a one-tailed test and the reality is that you would be unlikely to get published if you used them, or at least you would be asked to make corrections. Personally though, in project work, I can see no great tragedy lying in wait for those who do use one-tailed tests so long as they are conscientious, honest and professional in their overall approach to research, science and publishing. As a student, however, you should just pay attention to the following things:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>follow the universally accepted \u2018rules\u2019 given in the main text;<\/li>\n\n\n\n<li>be aware that this is a debate, and be prepared for varying opinions around it;<\/li>\n\n\n\n<li>try to test enough participants (as Bradley advises), pilot your design and tighten it, so that you are likely to obtain significance at p \u2264 .01, let alone .05!<\/li>\n\n\n\n<li>the issue of two-tailed tests mostly disappears once we leave simple two-condition tests behind. In ANOVA designs there is no such issue.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For references, please see the textbook.<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"#_ftnref1\" id=\"_ftn1\">[1]<\/a> Sadly no longer available except via The British Film Institute<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\" style=\"flex-basis:25%\">\n<div class=\"wp-block-group is-vertical is-nowrap is-layout-flex wp-container-core-group-is-layout-b3ff8204 wp-block-group-is-layout-flex wp-container-1 is-position-sticky\">\n<p class=\"wp-block-paragraph\"><strong>On this page<\/strong><\/p>\n\n\n\n<nav class=\"wp-block-table-of-contents\"><ol><li><a class=\"wp-block-table-of-contents__entry\" href=\"https:\/\/routledgelearning.com\/researchmethods\/student-resources\/chapter-16-significance-testing-was-it-a-real-effect\/#aioseo-exercises\">Exercises<\/a><\/li><li><a class=\"wp-block-table-of-contents__entry\" href=\"https:\/\/routledgelearning.com\/researchmethods\/student-resources\/chapter-16-significance-testing-was-it-a-real-effect\/#aioseo-weblinks\">Weblinks<\/a><\/li><li><a class=\"wp-block-table-of-contents__entry\" href=\"https:\/\/routledgelearning.com\/researchmethods\/student-resources\/chapter-16-significance-testing-was-it-a-real-effect\/#aioseo-further-information\">Further Information<\/a><\/li><\/ol><\/nav>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>This chapter is about the principles of significance testing.&nbsp; Exercises Exercise 16.1 One- or two-tailed tests In each case below decide whether the research prediction permits a one-tailed test or whether a two-tailed test is obligatory. 1.There will be a difference between imagery and rehearsal recall scores. 2. Self-confidence will correlate with self-esteem 3.Extroverts will [&hellip;]<\/p>\n","protected":false},"featured_media":0,"parent":121,"menu_order":0,"template":"single-chapter","format":"standard","meta":{"_acf_changed":false},"categories":[],"class_list":["post-108","content","type-content","status-publish","format-standard","hentry"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO Pro 5.0.0.1 - aioseo.com -->\n\t<meta name=\"description\" content=\"This chapter is about the principles of significance testing. Exercises Exercise 16.1 One- or two-tailed tests In each case below decide whether the research prediction permits a one-tailed test or whether a two-tailed test is obligatory. 1.There will be a difference between imagery and rehearsal recall scores. 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Exercises Exercise 16.1 One- or two-tailed tests In each case below decide whether the research prediction permits a one-tailed test or whether a two-tailed test is obligatory. 1.There will be a difference between imagery and rehearsal recall scores. 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Exercises Exercise 16.1 One- or two-tailed tests In each case below decide whether the research prediction permits a one-tailed test or whether a two-tailed test is obligatory. 1.There will be a difference between imagery and rehearsal recall scores. 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