5. Moderator variables - "In general terms, a moderator is a qualitative (e.g., sex, race, class) or quantitative (e.g., level of reward) variable that affects the direction and/or strength of the relation between an independent or predictor variable and a dependent or criterion variable. Consider a case in which a variable M is presumed to change the X to Y causal relationship. So for instance, a certain form of psychotherapy may reduce depression more for men than for women, and so we would say that gender ( M ) moderates the causal effect of psychotherapy ( X ) on depression ( Y ).. Variables must be defined in terms of measurable behaviors. The operational definition of a variable describes the variable. There are two ways by which we can operationally define a variable; by how it is measured and by how it is used to classify subjects. Later we will use specialized terms for how variables are defined (continuous or categorical) and the nature of the data obtained (nominal, ordinal, or interval). The first way of defining a variable is to describe how we measure it. We cannot just say we will "reduce anxiety." We must define how anxiety will be measured and just what is a reduction in anxiety. The second way of defining a variable is to describe how you have classified subjects (people) into groups or categories. This is important since two researchers could be studying the same variable but if they each classify their subjects differently they may get different results. For example, suppose we wanted to study the income levels of single adults. If one researcher classified his single adult subjects into these three categories (17 through 22, 23 through 27, and 28 through 33), he would get different results than this second researcher who used three different categories (20 through 40, 41 through 60, and 61 and over). The first researcher is interested in young adults and the second in all ages. Thus, without operational definitions we could think that they both were studying the same variable. When
36 | P a g e we use behavioral (operational) definitions for variables, we define exactly what we are studying and enable others to understand our work. This is called operationalisation of terms or variables. HYPOTHESES: Once the research question has been stated, the next step is to define testable hypotheses. Usually a research question is a broad statement, that is not directly measurable by a research study. The research question needs to be broken down into smaller units, called hypotheses, that can be studied. A hypothesis is a statement that expresses the probable relationship between variables. The problem thus delimited to make it more specific & manageable, several interrelated steps, e.g. formulation of hypotheses, explication of concepts that enter into the hypotheses & consideration of methods for relating the study to other studies using similar or kindred concepts. These steps are so closely intertwined that they cannot be worked on, one at a time.
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- Winter '17