Ch. 5: Variables and Hypotheses

Ch. 5: Variables and Hypotheses

1. The Importance of Studying Relationships

   • Identifying Relationships among variables enhances understanding
   • Understanding relationships helps us to explain the nature of our world

2. Variables

   • A variable is any characteristic or quality the varies among the members of a particular group
   • A constant is any characteristic or quality that is the same for all members of a particular group
   • A quantitative variable varies in amount or degree, but not in kind
   • A categorical variable varies only in kind, not in degree or amount
   • Several kinds of variables are studied in education research, the most common being independent and dependent variables
     • An independent variable is presumed to affect or influence other variables
       • Independent variables are sometimes called experimental variables or manipulated variables
         • Independent variables may either be manipulated or selected
           • A manipulated variable is created by the researcher
           • A selected variable is one that already exists that the researcher locates and then chooses to study
       • A moderator variable is a secondary independent variable that the researcher selects to study because he or she thinks it may affect the basic relationship between the primary independent variable and the dependent variable
       • An extraneous variable is an independent variable that may have unintended effects on a dependent variable in a particular study
     • A dependent (or outcome) variable is presumed to directly affect or influence other variables
   • A proposition is a tentative, flexible statement used sometimes by qualitative researchers to help guide their data collection and analysis

3. Hypotheses

   • The term, hypothesis, as used in research, refers to a prediction of results usually made before a study commences
     • Stating a research question as a hypothesis has both advantages and disadvantages
     • An important hypothesis is one that is likely to lead, if it is supported, to a greater amount of important knowledge than a non important hypothesis
       • A directional hypothesis is a prediction about the specific nature of a relationship--for example, method A is more effective than method B
       • A nondirectional hypothesis is a prediction that a relationship exists without specifying its exact nature--for example, there will be a difference between method A and method B (without saying which will be more effective)