Discussion: The Logic of Inference: The Science of Uncertainty
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SkillBuilder1_IndependentandDependentVariables-DistinguishBetweenaVariableandaValue.htmlDistinguish Between a Variable and a Value
Topic 1 of 4Learning Objective:
Distinguish between independent and dependent variables
Words in orange represent glossary terms. You can locate the Glossary in Appendix 1.
Variables and Values
The ultimate goal of science is to identify and explain cause-and-effect relationships among events in the real world. For example, a researcher may want to understand how a person can grow thicker hair. This researcher may think that using high-quality shampoo, specifically Ultra Shampoo, will result in thicker hair. How should the researcher structure questions about whether this specific shampoo brand promotes thick and luxurious hair?
A quantitative researcher’s approach to this problem begins by using variables. A variable is a mathematical representation of the real-world entity being measured. For example, the researcher could decide that “use” or “non-use” of Ultra Shampoo is one variable. A measure of hair quality, as judged by a professional hairstylist, could be a second variable.
Variables are sometimes called attributes, traits, or constructs and can actually take on two or more values. The value of a variable is defined as a single observation for the variable. Going back to the example, if a person uses Ultra Shampoo, the researcher could code “Yes” as a value for the use of the Ultra Shampoo variable and "No" for its non-use. Similarly, a “10,” corresponding to perfect hair, could be a value for a single person on the hair quality variable.
The image below shows how variables and values appear in data sets. Note that a person’s name is used as a variable so that the name will identify the values for the study participant on the other two variables.
