The Variant of Research Models: Correlational Research

Definition: Whether and to what degree variables are related

Purpose:

Determine relationships

Make predictions

Limitation: Cannot indicate cause and effect

Problem selection

• Variables to be correlated are selected on the basis of some rationale:
• Math attitudes and math achievement
• Teachers’ sense of efficacy and their effectiveness
• Increases the ability to meaningfully interpret results

Inefficiency and difficulty interpreting the results from a shotgun approach

Participant and instrument selection

• Minimum of 30 subjects
• Instruments must be valid and reliable
• Higher validity and reliability requires smaller samples
• Lower validity and reliability requires larger samples

Design and procedures: Collect data on two or more variables for each subject

Data analysis: Compute the appropriate correlation coefficient

 

Correlation Coefficients

A correlation coefficient identifies the size and direction of a relationship

Size/magnitude: Ranges from 0.00 – 1.00

Direction: Positive or negative

Interpreting the size of correlations

General rule:

• Less than .35 is a low correlation
• Between .36 and .65 is a moderate correlation
• Above .66 is a high correlation

Predictions:

• Between .60 and .70 are adequate for group predictions
• Above .80 is adequate for individual predictions

Interpreting the size of correlations (cont.)

Criterion-related validity

• Above .60 for affective scales is adequate
• Above .80 for tests is minimally acceptable

Inter-rater reliability

• Above .90 is very good
• Between .80 and .89 is acceptable
• Between .70 and .79 is minimally acceptable
• Lower than .69 is problematic

Interpreting the direction of correlations

Direction

Positive

High scores on the predictor are associated with high scores on the criterion
Low scores on the predictor are associated with low scores on the criterion

Negative

High scores on the predictor are associated with low scores on the criterion
Low scores on the predictor are associated with high scores on the criterion

Positive or negative does not mean good or bad