{"id":312,"date":"2016-10-10T20:07:00","date_gmt":"2016-10-10T20:07:00","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/math4libarts\/?post_type=chapter&#038;p=312"},"modified":"2022-01-07T00:34:52","modified_gmt":"2022-01-07T00:34:52","slug":"4-7-observational-studies-and-experiments","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/frontrange-mathforliberalartscorequisite1\/chapter\/4-7-observational-studies-and-experiments\/","title":{"raw":"4.7 Observational Studies and Experiments","rendered":"4.7 Observational Studies and Experiments"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Identify the differences between observational studies and experiments<\/li>\r\n<\/ul>\r\n<\/div>\r\n<div class=\"textbox examples\">\r\n<h3>Read with a pencil in hand<\/h3>\r\nContinue to read these sections with a pencil in hand. Make note of definitions, but also make note of keywords that will help you to identify an observational study versus an experiment. Work the TRY IT and EXAMPLES out by hand to gain the experience you'll need to correctly identify these on a test.\r\n\r\n<\/div>\r\n<h2>What you\u2019ll learn to do: Examine the methods for sampling and experimentation and how bias can affect the results<\/h2>\r\nAs we mentioned previously, the first thing we should do before conducting a survey is to identify the population that we want to study. In this lesson, we will show you examples of how to identify the population in a study, and determine whether or not the study actually represents the intended population. We will discuss different techniques\u00a0for <em>random sampling<\/em> that are intended to ensure a population is well represented in a sample.\r\n\r\nWe will also identify the difference between an observational study and an experiment, and ways experiments can be conducted. By the end of this lesson, we hope that you will also be confident in identifying when an experiment may have\u00a0been affected by confounding or the placebo effect, and the methods that are employed to avoid them.\r\n<h2>Observing vs. Acting<\/h2>\r\nSo far, we have primarily discussed <strong>observational studies<\/strong> \u2013 studies in which conclusions would be drawn from observations of a sample or the population. In some cases these observations might be unsolicited, such as studying the percentage of cars that turn right at a red light even when there is a \u201cno turn on red\u201d sign. In other cases the observations are solicited, like in a survey or a poll.\r\n\r\nIn contrast, it is common to use <strong>experiments<\/strong> when exploring how subjects react to an outside influence. In an experiment, some kind of <strong>treatment<\/strong> is applied to the subjects and the results are measured and recorded.\r\n\r\n<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2016\/12\/30181148\/lab-217041_640.jpg\"><img class=\"aligncenter size-full wp-image-1033\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2016\/12\/30181148\/lab-217041_640.jpg\" alt=\"Collection of clear glass scientific measuring equipment, with clear liquid in them\" width=\"640\" height=\"423\" \/><\/a>\r\n<div>\r\n<div class=\"textbox\">\r\n<div>\r\n<h3>Observational studies and experiments<\/h3>\r\n<\/div>\r\n<div>\r\n<ul>\r\n \t<li>An <strong>observational study<\/strong> is a study based on observations or measurements<\/li>\r\n \t<li>An <strong>experiment<\/strong> is a study in which the effects of a <strong>treatment<\/strong> are measured<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox exercises\">\r\n<h3>Examples<\/h3>\r\nHere are some examples of experiments:\r\n\r\nA pharmaceutical company tests a new medicine for treating Alzheimer\u2019s disease by administering the drug to 50 elderly patients with recent diagnoses. The treatment here is the new drug.\r\n\r\n<hr \/>\r\n\r\nA gym tests out a new weight loss program by enlisting 30 volunteers to try out the program. The treatment here is the new program.\r\n\r\n<hr \/>\r\n\r\nYou test a new kitchen cleaner by buying a bottle and cleaning your kitchen. The new cleaner is the treatment.\r\n\r\n<hr \/>\r\n\r\nA psychology researcher explores the effect of music on temperament by measuring people\u2019s temperament while listening to different types of music. The music is the treatment.\r\n\r\n<\/div>\r\n&nbsp;\r\n\r\nThese examples are discussed further in the following video.\r\n\r\nhttps:\/\/youtu.be\/HSTTKzsdHEw\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Try It<\/h3>\r\nIs each scenario describing an observational study or an experiment?\r\n\r\na. The weights of 30 randomly selected people are measured\r\n\r\nb. Subjects are asked to do 20 jumping jacks, and then their heart rates are measured\r\n\r\nc. Twenty coffee drinkers and twenty tea drinkers are given a concentration test\r\n[reveal-answer q=\"713031\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"713031\"]\r\n\r\na. Observational study\r\n<div>\r\n\r\nb. Experiment; the treatment is the jumping jacks\r\n\r\nc. Experiment; the treatments are coffee and tea\r\n\r\n<\/div>\r\n[\/hidden-answer]\r\n\r\n[ohm_question]6914[\/ohm_question]\r\n\r\n<\/div>\r\n<p style=\"text-align: center;\"><strong><span style=\"color: #ff0000;\">This is the end of the section. Close this tab and proceed to the corresponding assignment.<\/span><\/strong><\/p>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Identify the differences between observational studies and experiments<\/li>\n<\/ul>\n<\/div>\n<div class=\"textbox examples\">\n<h3>Read with a pencil in hand<\/h3>\n<p>Continue to read these sections with a pencil in hand. Make note of definitions, but also make note of keywords that will help you to identify an observational study versus an experiment. Work the TRY IT and EXAMPLES out by hand to gain the experience you&#8217;ll need to correctly identify these on a test.<\/p>\n<\/div>\n<h2>What you\u2019ll learn to do: Examine the methods for sampling and experimentation and how bias can affect the results<\/h2>\n<p>As we mentioned previously, the first thing we should do before conducting a survey is to identify the population that we want to study. In this lesson, we will show you examples of how to identify the population in a study, and determine whether or not the study actually represents the intended population. We will discuss different techniques\u00a0for <em>random sampling<\/em> that are intended to ensure a population is well represented in a sample.<\/p>\n<p>We will also identify the difference between an observational study and an experiment, and ways experiments can be conducted. By the end of this lesson, we hope that you will also be confident in identifying when an experiment may have\u00a0been affected by confounding or the placebo effect, and the methods that are employed to avoid them.<\/p>\n<h2>Observing vs. Acting<\/h2>\n<p>So far, we have primarily discussed <strong>observational studies<\/strong> \u2013 studies in which conclusions would be drawn from observations of a sample or the population. In some cases these observations might be unsolicited, such as studying the percentage of cars that turn right at a red light even when there is a \u201cno turn on red\u201d sign. In other cases the observations are solicited, like in a survey or a poll.<\/p>\n<p>In contrast, it is common to use <strong>experiments<\/strong> when exploring how subjects react to an outside influence. In an experiment, some kind of <strong>treatment<\/strong> is applied to the subjects and the results are measured and recorded.<\/p>\n<p><a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2016\/12\/30181148\/lab-217041_640.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-1033\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2016\/12\/30181148\/lab-217041_640.jpg\" alt=\"Collection of clear glass scientific measuring equipment, with clear liquid in them\" width=\"640\" height=\"423\" \/><\/a><\/p>\n<div>\n<div class=\"textbox\">\n<div>\n<h3>Observational studies and experiments<\/h3>\n<\/div>\n<div>\n<ul>\n<li>An <strong>observational study<\/strong> is a study based on observations or measurements<\/li>\n<li>An <strong>experiment<\/strong> is a study in which the effects of a <strong>treatment<\/strong> are measured<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<div class=\"textbox exercises\">\n<h3>Examples<\/h3>\n<p>Here are some examples of experiments:<\/p>\n<p>A pharmaceutical company tests a new medicine for treating Alzheimer\u2019s disease by administering the drug to 50 elderly patients with recent diagnoses. The treatment here is the new drug.<\/p>\n<hr \/>\n<p>A gym tests out a new weight loss program by enlisting 30 volunteers to try out the program. The treatment here is the new program.<\/p>\n<hr \/>\n<p>You test a new kitchen cleaner by buying a bottle and cleaning your kitchen. The new cleaner is the treatment.<\/p>\n<hr \/>\n<p>A psychology researcher explores the effect of music on temperament by measuring people\u2019s temperament while listening to different types of music. The music is the treatment.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p>These examples are discussed further in the following video.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Experiments\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/HSTTKzsdHEw?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Try It<\/h3>\n<p>Is each scenario describing an observational study or an experiment?<\/p>\n<p>a. The weights of 30 randomly selected people are measured<\/p>\n<p>b. Subjects are asked to do 20 jumping jacks, and then their heart rates are measured<\/p>\n<p>c. Twenty coffee drinkers and twenty tea drinkers are given a concentration test<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q713031\">Show Solution<\/span><\/p>\n<div id=\"q713031\" class=\"hidden-answer\" style=\"display: none\">\n<p>a. Observational study<\/p>\n<div>\n<p>b. Experiment; the treatment is the jumping jacks<\/p>\n<p>c. Experiment; the treatments are coffee and tea<\/p>\n<\/div>\n<\/div>\n<\/div>\n<p><iframe loading=\"lazy\" id=\"ohm6914\" class=\"resizable\" src=\"https:\/\/ohm.lumenlearning.com\/multiembedq.php?id=6914&theme=oea&iframe_resize_id=ohm6914&show_question_numbers\" width=\"100%\" height=\"150\"><\/iframe><\/p>\n<\/div>\n<p style=\"text-align: center;\"><strong><span style=\"color: #ff0000;\">This is the end of the section. Close this tab and proceed to the corresponding assignment.<\/span><\/strong><\/p>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-312\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Original<\/div><ul class=\"citation-list\"><li>Revision and Adaptation. <strong>Provided by<\/strong>: Lumen Learning. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Experiments. <strong>Authored by<\/strong>: David Lippman. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.opentextbookstore.com\/mathinsociety\/\">http:\/\/www.opentextbookstore.com\/mathinsociety\/<\/a>. <strong>Project<\/strong>: Math in Society. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA: Attribution-ShareAlike<\/a><\/em><\/li><li>lab-research-chemistry-test. <strong>Authored by<\/strong>: PublicDomainPictures. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/pixabay.com\/en\/lab-research-chemistry-test-217041\/\">https:\/\/pixabay.com\/en\/lab-research-chemistry-test-217041\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/about\/cc0\">CC0: No Rights Reserved<\/a><\/em><\/li><li>Experiments. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/HSTTKzsdHEw\">https:\/\/youtu.be\/HSTTKzsdHEw<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Confounding. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/SrCm12HZay0\">https:\/\/youtu.be\/SrCm12HZay0<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Controlled Experiments. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/UkCHUeqMb5Y\">https:\/\/youtu.be\/UkCHUeqMb5Y<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Blind Experiments. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/7BFZVGCxeYc\">https:\/\/youtu.be\/7BFZVGCxeYc<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Question ID 6736, 6728, 6914. <strong>Authored by<\/strong>: Lippman, David. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: IMathAS Community License CC-BY + GPL<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":20,"menu_order":10,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"Experiments\",\"author\":\"David Lippman\",\"organization\":\"\",\"url\":\"http:\/\/www.opentextbookstore.com\/mathinsociety\/\",\"project\":\"Math in Society\",\"license\":\"cc-by-sa\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"lab-research-chemistry-test\",\"author\":\"PublicDomainPictures\",\"organization\":\"\",\"url\":\"https:\/\/pixabay.com\/en\/lab-research-chemistry-test-217041\/\",\"project\":\"\",\"license\":\"cc0\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Experiments\",\"author\":\"OCLPhase2\\'s channel\",\"organization\":\"\",\"url\":\"https:\/\/youtu.be\/HSTTKzsdHEw\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Confounding\",\"author\":\"OCLPhase2\\'s channel\",\"organization\":\"\",\"url\":\"https:\/\/youtu.be\/SrCm12HZay0\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Controlled Experiments\",\"author\":\"OCLPhase2\\'s channel\",\"organization\":\"\",\"url\":\"https:\/\/youtu.be\/UkCHUeqMb5Y\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Blind Experiments\",\"author\":\"OCLPhase2\\'s channel\",\"organization\":\"\",\"url\":\"https:\/\/youtu.be\/7BFZVGCxeYc\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Question ID 6736, 6728, 6914\",\"author\":\"Lippman, David\",\"organization\":\"\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"IMathAS Community License CC-BY + GPL\"},{\"type\":\"original\",\"description\":\"Revision and Adaptation\",\"author\":\"\",\"organization\":\"Lumen 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