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Section 1: VariablesThe purpose of all research is to describe and explain variance in the world. Variance is simply the difference; that is, variation that occurs naturally in the world or change that we create as a result of a manipulation. Variables are names that are given to the variance we wish to explain. A variable is either a result of some force or is itself the force that causes a change in another variable. In experiments, these are called dependent and independent variables respectively. This could be many things depending upon what the medication is for, such as high blood pressure or muscle pain. Therefore, in experiments, a researcher manipulates an independent variable to determine if it causes a change in the dependent variable. As we learned earlier in a descriptive study, variables are not manipulated. They are observed as they naturally occur and then associations between variables are studied. In a way, all the variables in descriptive studies are dependent variables because they are studied in relation to all the other variables that exist in the setting where the research is taking place. However, in descriptive studies, variables are not discussed using the terms "independent" or "dependent." Instead, the names of the variables are used when discussing the study. For example, there is more diabetes in people of Native American heritage than people who come from Eastern Europe. In a descriptive study, the researcher would examine how diabetes (a variable) is related to a person's genetic heritage (another variable). Definition: A variable is either a result of some force or it is the force that causes a change in another variable. In experiments, these are called dependent and independent variables respectively. Case Examples for Independent and Dependent VariablesExample 1: Example 2: Section 1: Discussion Questions
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Variables are important to understand because they are the basic units of the information studied and interpreted in research studies. Researchers carefully analyze and interpret the value(s) of each variable to make sense of how things relate to each other in a descriptive study or what has happened in an experiment. Definition: Variables are characteristics studied in research that can take on different values (e.g., weight, height, exposure to a substance, demographics (i.e., where you live, your ethnicity, how much income you have, medical background). Case Example for Descriptive Study VariablesSee if you can identify the variables that are under investigation in the following descriptive study:Many children who live in the Bronx, a borough of New York City, are developing asthma. In a descriptive study investigating this problem, parents whose children have asthma are asked about whether they smoke around their child, whether they live near a freeway, whether their child regularly sees a healthcare provider, their family income level and also if there is a history in their family of asthma. Prior research has shown that these factors may have an influence on the development of asthma in children. Section 1: Discussion Questions
What is the term for an experiment in which neither the participants nor the researchers know who is assigned to the experimental or control groups?A double-blind study is one in which neither the participants nor the experimenters know who is receiving a particular treatment. This procedure is utilized to prevent bias in research results.
Is a study in which the researcher knows which groups the participants are in while the participants do not?In a single-blind study, the researcher knows which group each participant is assigned to and the variable being evaluated. A single-blind experiment is important if the research subjects are likely to bias or compromise the data if they know what is being tested and which group they are assigned to.
What kind of experiment or study is one in which neither the subjects nor the researcher taking the measurements knows who had which treatment?In a double-blind experiment, neither the subjects nor those who interact with them and measure the response variable know which treatment a subject received. The placebo effect describes the fact that some subjects in an experiment will respond favorably to any treatment, even an inactive treatment.
What is a placebo group in research?That means volunteers are randomly assigned—that is, selected by chance—to either a test group receiving the experimental intervention or a control group receiving a placebo or standard care. A placebo is an inactive substance that looks like the drug or treatment being tested.
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