correlational research
TRANSCRIPT
CORRELATIONAL RESEARCH
QUANTITATIVE RESEARCH METHODOLOGIES
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
PURPOSES OF CORRELATIONAL RESEARCH
• Two basic purposes
1. Help explain important human behaviors
(Explanatory Studies)
2. Predict likely outcomes
(Prediction Studies)
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
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
Using Scatter plots to Predict a Score
• We can use the scatter plots to find a correlation between the variables
• correlational research.pptx
A simple Prediction Equation
• Used to express the regression line
• We gain confidence in using the prediction equation to make future predictions if there is a close similarity between two results
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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
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
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
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.
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?
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).
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
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.
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
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
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
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.
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