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# Correlational research

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• 1. QUANTITATIVE RESEARCH METHODOLOGIESCORRELATIONAL RESEARCH
• 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 purposes1. 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 TECHNIQUES1. 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 categorical5. Factor Analysis• Technique that allows a researcher to determine if many variables can be described by a few factors.
• 12. BASIC STEPS IN CORRELATIONAL RESEARCH1. 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 research1. 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 others3. 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 instrument5. 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 correlation3. 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