Variables and Hypotheses

1. Variables and Hypotheses S. Kathleen Kitao Kenji Kitao Keywordsvariable, hypothesis, independent variable, dependent variable

2. will discuss • variables • hypotheses • independent variables • dependent variables

3. Variables • Definition • something that can be different in different people or in different circumstances, that is, something that can vary • Examples • sex • English proficiency • income • nationality • IQ scores

4. Why variables are important • in quantitative research, they are what the researchers measure • Researchers in quantitative studies look at • how variables are different in different groups • how variables change over time • how a change in circumstances can change the variable.

5. Some variables have only a limited number of values, while others have a range of values. • Sex has to be either male or female -- it has only two values. • A single study would probably only use a few nationalities, say, English, American, Australian, French, and German. • A test of English proficiency, however, might have values ranging from zero points to 100 points. • Even for values with a range, however, the researcher can specify a limited number of values.

6. Hypotheses • Definition • A hypothesis states the relationship between two or more variables. • Examples • “Americans find rational arguments more persuasive, while Japanese find emotional arguments more persuasive.” • Variables • 1. nationality (Japanese or American) • 2. the type or argument (emotional or rational)

7. 2. “Friends in Internet relationships exchange more personal information than friends in face-to-face relationships.” • Variables • 1. type of friendship (internet friendship vs. face-to-face friendship) • 2. amount of personal information exchanged

8. 3. “A woman wearing a suit will be judged as more intelligent than one who is wearing jeans and a t-shirt.” • Variables • 1. Judgments about intelligence • 2. type of clothing

9. The purpose of a research study is to test hypotheses or answer research questions. • A researcher makes a hypothesis based on what is known about the subject from previous research. • A researcher can also make a hypothesis based on what seems logical.

10. If a researcher does not have enough information to make a hypothesis, he/she can make a research question. • Examples • "How is the amount of personal information exchanged in Internet and personal relationships different?" • "How do people judge a woman wearing a suit and a woman wearing a t-shirt differently?"

11. Dependent and Independent Variables • Definitions • Independent variables are variables that, according to the hypothesis, are a cause of, or have an influence on, another variable. • Dependent variables are variables that, according to the hypothesis, are an effect of, or are affected by, another variable.

12. Variables are not inherently dependent or independent, that is, most variables can be either dependent or independent, depending on how they are linked to other variables in a hypothesis.

13. Examples • 1. “Females reveal more personal information about themselves than males.” • Independent variable: sex • Dependent variable: how much personal information is revealed • 2. “People who reveal more personal information form closer friendships.” • Independent variable: how much personal information is revealed • Dependent variable: closeness of friendships

14. In the first case, the amount of personal information revealed is a dependent variable, and in the second case, the amount of personal information revealed is the independent variable. • Therefore, a particular variable can be either independent or dependent, depending on the hypothesis.

15. Control Variables • Definition • Control variables are variables that the researcher is not studying, but which might affect the dependent variable. • Control variables must be kept the same, or controlled, since they may have an effect on the dependent variable.

16. Example • If the hypothesis states that students with higher language proficiency scores will attain a higher grade point average (GPA), it might be necessary to control for intelligence, since intelligence might also influence GPA.

17. Control variables are used in different ways. • One way is to use statistical methods to compare the language proficiency scores and GPA of students with the same IQ scores. • Another way is to choose only one value for the variable. For example, if you think men and women will be different, you might want to do your study on only women.

18. When you read a research paper, you should consider whether the research took other variables into account, and whether there were other variables that might have had an influence.

19. Conclusion • Among the important concepts in research are variables and hypotheses. • A variable is anything that can vary; a hypothesis is a statement of the relationship between variables.

20. When variables are put together into a hypothesis, one of the variables is independent, and the other is dependent. • The dependent variable is caused or influenced by the independent variable.