{"id":1852,"date":"2023-04-14T15:15:16","date_gmt":"2023-04-14T15:15:16","guid":{"rendered":"https:\/\/content.one.lumenlearning.com\/quantitativereasoning\/?post_type=chapter&p=1852"},"modified":"2025-08-27T00:26:02","modified_gmt":"2025-08-27T00:26:02","slug":"sampling-and-experimentation-learn-it-5","status":"web-only","type":"chapter","link":"https:\/\/content.one.lumenlearning.com\/quantitativereasoning\/chapter\/sampling-and-experimentation-learn-it-5\/","title":{"raw":"Sampling and Experimentation: Learn It 5","rendered":"Sampling and Experimentation: Learn It 5"},"content":{"raw":"

Experiments<\/h2>\r\n

So far, we have primarily discussed 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>\r\n

In contrast, it is common to use experiments<\/strong> when exploring how subjects react to an outside influence. In an experiment, some kind of treatment<\/strong> is applied to the subjects and the results are measured and recorded.<\/p>\r\n

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observational studies and experiments<\/h3>\r\n
    \r\n\t
  • An observational study<\/strong> is a study based on observations or measurements<\/li>\r\n\t
  • An experiment<\/strong> is a study in which the effects of a treatment<\/strong> are measured<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/section>\r\n
    Here are some examples of experiments: A pharmaceutical company tests a new medicine for treating Alzheimer\u2019s disease by administering the drug to [latex]50[\/latex] elderly patients with recent diagnoses. The treatment here is the new drug.\r\n
    \r\n

    A gym tests out a new weight loss program by enlisting [latex]30[\/latex] volunteers to try out the program. The treatment here is the new program.<\/p>\r\n

    \r\n

    You test a new kitchen cleaner by buying a bottle and cleaning your kitchen. The new cleaner is the treatment.<\/p>\r\n

    \r\n

    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>\r\n<\/section>\r\n

    [ohm2_question hide_question_numbers=1]6914[\/ohm2_question]<\/section>\r\n

    Experimental and Control Groups<\/h2>\r\n

    An important aspect of all experiments is a comparison between one or more groups or levels of the factor of interest, called treatments<\/b>. In a simple experimental design, one group receives the researcher\u2019s treatment and the other group does not. The group that receives the treatment is commonly called the experimental group<\/strong>. The group that does not receive the treatment is usually called the control group<\/strong>. The control group is usually kept under conditions that are considered typical or common for a given situation.<\/p>\r\n

    \r\n[caption id=\"attachment_3597\" align=\"aligncenter\" width=\"801\"]\"Diagram Figure 1. A diagram defining a control group and an experimental group[\/caption]\r\n<\/center>\r\n

     <\/p>\r\n

    It is important to remember that the only difference between the experimental and control groups is the researcher\u2019s manipulation of the factor of interest.<\/p>\r\n

    [ohm2_question hide_question_numbers=1]698[\/ohm2_question]<\/section>","rendered":"

    Experiments<\/h2>\n

    So far, we have primarily discussed 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

    In contrast, it is common to use experiments<\/strong> when exploring how subjects react to an outside influence. In an experiment, some kind of treatment<\/strong> is applied to the subjects and the results are measured and recorded.<\/p>\n

    \n
    \n

    observational studies and experiments<\/h3>\n
      \n
    • An observational study<\/strong> is a study based on observations or measurements<\/li>\n
    • An experiment<\/strong> is a study in which the effects of a treatment<\/strong> are measured<\/li>\n<\/ul>\n<\/div>\n<\/section>\n
      Here are some examples of experiments: A pharmaceutical company tests a new medicine for treating Alzheimer\u2019s disease by administering the drug to [latex]50[\/latex] elderly patients with recent diagnoses. The treatment here is the new drug.<\/p>\n
      \n

      A gym tests out a new weight loss program by enlisting [latex]30[\/latex] volunteers to try out the program. The treatment here is the new program.<\/p>\n

      \n

      You test a new kitchen cleaner by buying a bottle and cleaning your kitchen. The new cleaner is the treatment.<\/p>\n

      \n

      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<\/section>\n