The document discusses the definition and categorization of variables in research, including independent, dependent, control, extraneous, and moderator variables. It explains the significance of hypotheses, distinguishing between null and research hypotheses, and the implications of their relationships within a study. Additionally, it emphasizes the importance of precise measurement for better utility of variables and the impact of various factors on research outcomes.

2.  Variables are a class of outcomes that can take on more
than one value. Eg. include: Height, Weight, Social
class, Color
 Variables can therefore be further divided into specific
categories or attributes
 Eg. Social Class: Underclass Lower Class, Working
Class, Middle Class, Upper Class
 The more precisely a variable is measured, the more
useful the measurement is

7. Independent
Dependent
 Represents the
treatments or conditions
that the researcher has
either direct or indirect
control over to test their
effects on a particular
outcome.
 At least two different
values of the
independent variable
must be present  reflects the outcomes of a
research study.

8.  The longer you spend on a task the better the
results.
 People who attend church regularly are more
likely to oppose abortion
 Educated women are likely to have fewer
children

9. Type of
Variable
Definition Other Terms You
Might See
Dependent
A variable that is measured to see whether the treatment or
manipulation of the independent variable had an effect
• Outcome variable
• Results variable
• Criterion variable
Independent
A variable that is manipulated to examine its impact on a
dependent variable
• Treatment
• Factor
• Predictor variable
Control
A variable that is related to the dependent variable, the
influence of which needs to be removed
• Restricting variable
Extraneous
A variable that is related to the dependent variable or
independent variable that is not part of the experiment
• Threatening variable
Moderator
A variable that is related to the dependent variable or
independent variable and has an impact on the dependent
variable
• Interacting variable

10. “An educated guess”

11.  Reflects the general problem under study
 Restates the general problem in a form
that is precise enough to allow testing
 Two types:
❑ Null Hypothesis
❑ Research Hypothesis

12.  States that there is no relationship between the
independent and dependent variables under
study : Ho = the symbol for the null hypothesis
❑ There will be no difference in the average score of ninth graders and
the average score of twelfth graders on the ABC memory test.
❑ There is no relationship between personality type and job success.
❑ There is no difference in voting patterns as a function of political
party.

13.  A starting point for analysis
 Accepted as true absent other information
 Assumes that chance caused any observed
differences
 Provides a benchmark for comparison

14.  Whereas a null hypothesis is a statement of no relationship
between variables, a research hypothesis is a definite
statement of the relationship between two variables.
Nondirectional Research Hypothesis
 Groups are different, but direction is not specified
 Teachers who are more knowledgeable about HIV/AIDS treat their
students differently than those who do not know as much.
Directional Research Hypothesis
 Groups are different, and direction is specified
 Teachers who are more knowledgeable about HIV/AIDS treat their
students who are infected better than those who do not know as much.

15.  Is stated in declarative form
 Posits a relationship between variables
 Reflects theory or literature
 Is brief and to the point
 Is testable