VARIABLES AND HYPOTHESES
Variable is any characteristic or quality that varies among the members of a particular group, such as gender, eye color, achievement, motivation or running speed.
Constant is any characteristic or quality that is the same for all members of a particular group, such as individual members of the class.
A quantitative variable varies in amount or degree, but not in kind. Two obvious examples are height (Anton is 170 cm and Kamal is 149 cm) and weight (Rita weighs only 50 kg and Sri weighs 48 kg).
A categorical variable varies only in kind, not in degree or amount. Examples include eye color, gender, religious preference, and occupation.
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 (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.
Anxiety affects test performance, but the correlation is markedly lower for students with test-taking experience.
Independent variable : anxiety level
Moderator variable : test-taking experience
Dependent variable : test performance
The term hypothesis, as used in research, refers to prediction of results usually made before a study commences. For example:
Question: Will students who are taught mathematics by a teacher of the same gender like the subject more than students taught by a teacher of a different gender?
Hypothesis: Students taught mathematics by a teacher of the same gender will like the subject more than students taught mathematics by a teacher of a different gender.
Question: Do second-graders like school less than they like watching television.
Hypothesis: Second-graders like school less than they like watching television.
Advantages of stating hypotheses in addition to research questions:
A hypothesis forces us to think more deeply and specifically about the possible outcomes of a study.
A hypothesis enables one to make specific predictions based on prior evidence or theoretical argument.
Stating a hypothesis help us see if we are investigating a relationship.
Disadvantages of stating hypotheses:
Stating a hypothesis may lead to a bias, either conscious or unconscious, on the part of the researcher.
It may sometimes be unnecessary, or even inappropriate.
Focusing attention on a hypothesis may prevent researchers from noticing other phenomena that might be important to study.
Directional versus nondirectional hypotheses
A directional hypothesis is a prediction about the specific nature of a relationship, for example, PMRI approach is more effective conventional approach.
A nondirectional hypothesis is a prediction that a relationship exists without specifying its exact nature-for example, there will be a difference between PMRI approach and conventional approach.