2. THE NATURE OF
CORRELATIONAL RESEARCH
• Sometimes called associational research
• It investigates the possibility of relationships
between only two variables
• Also sometimes referred to as a form of
descriptive research
• Describes the degree to which two or more
quantitative variables are related
3. PURPOSES OF CORRELATIONAL
RESEARCH
• Two basic purposes
1. Help explain important human behaviors
(Explanatory Studies)
2. Predict likely outcomes
(Prediction Studies)
4. EXPLANOTARY STUDIES
• Researchers often investigate a number of
variables they believe are related to a more
complex variable.
• Unrelated variables dropped from further
consideration
• Most researchers most probably trying to
gain some ideas about cause and effect
• However it does not establish cause and
effect
5. PREDICTION STUDIES
• Predict a score on one variable if a score on
the other variable is known
• Determine the predictive validity of
measuring instruments
• Predictor Variable; variable that is used to
make the prediction
• Criterion Variable; variable about which the
prediction is made
6. Using Scatter plots to Predict a Score
• We can use the scatter plots to find a
correlation between the variables
• correlational research.pptx
7. A simple Prediction Equation
• Used to express the regression line
• We gain confidence in using the
Y'
prediction equation to make future
predictions if there is a close similarity
between two results
8. MORE COMPLEX
CORRELATIONAL TECHNIQUES
1. Multiple Regressions; technique that
enables researchers to determine a
correlation between a criterion variable
• The best combination of two or more
predictor variables
9. 2. The Coefficient of Multiple Correlation
• Symbolized by R; indicates the strength of
the correlation between the combination of
the predictor variables and the criterion
variables.
• multiple correlation.jpg
• The higher R is, the more reliable a
prediction will be
10. 3. The Coefficient of Determination
• The square of the correlation between a
predictor and a criterion variable
• Indicates the percentage of the variability
among the criterion scores that can be
attributed to differences in the scores on
the predictor variable
11. 4. Discriminant Function Analysis
• Technique used when the technique of
multiple regression cannot be used when
the criterion variable is categorical
5. Factor Analysis
• Technique that allows a researcher to
determine if many variables can be
described by a few factors.
12. BASIC STEPS IN
CORRELATIONAL RESEARCH
1. Problem Selection
• Three major types of problems;
a. is variable X related to variable Y?
b. how well does variable P predict variable C?
c. What are the relationship among a large
number of variables and what predictions can
be made?
13. 2. Sample
• Should be selected carefully, and if
possible, randomly.
• Not less than 30.
3. Instruments
• Most correlational studies involve the
administration of some types of
instruments (tests, questionnaire, and so
on).
14. 4. Design and Procedures
• Design used quite straightforward.
5. Data Collection
• Data on both variables will usually be
collected in a short time.
• Instruments used are administered in a
single session or two sessions
15. THREATS TO INTERNAL
VALIDITY
• There are some threats identified in
conducting correlational research
1. Subject Characteristics
• Individuals or groups have two or more
characteristics; might be a cause of
variation in the other two variables.
16. 2. Location
• Location is different for different subject
• One location may be more comfortable
compared to others
3. Instrumentation
• Instrument decay; care must be taken to ensure
the observers don’t become tired, bored or
inattentive
• Data collector characteristics; different gender,
age or ethnicity may affect specific response
17. 4. Testing
• Experience of responding to the first
instrument may influence subject responses
to the second instrument
5. Mortality
• Loss of subjects may make a relationship
more (or less) likely in the remaining data
18. EVALUATING THREATS TO
INTERNAL VALIDITY
• Follows a procedure similar to the
experimental research.
1. Subject Characteristics
• Four of many possible characteristics
a. Severity of disability
b. Socioeconomic level of parents
c. Physical strength and coordination
d. Physical appearance
19. 2. Mortality
• Loss of subjects can be expected to reduce
magnitude of correlation
3. Location
• Threats could be controlled by
independently assessing the job-site
environments.
20. 4. Instrumentation
• Instrument decay; observations should
scheduled
• Data collector characteristics; interaction of
data collectors and supervisors is a
necessary parts
• Data collector bias; observers should have
no knowledge of job ratings
