The Importance of Studying Relationships

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

Variables

• A variable is any characteristic or quality that 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 educational 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.
• A dependent (or outcome) variable is presumed to be affected by one or more independent variables.
• Independent variables may be either 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.

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.
• A significant hypothesis is one that is likely to lead, if it is supported, to a greater amount of important knowledge than a nonsignificant 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).