MEASURES of CORRELATION

CORRELATION

•basically the test of measurement.•Means that two variables tend to vary together•The presence of one indicates the presence of the other•One can be predicted from the presence of the other

The degree of relationship between variables is expressed into:

1. Perfect correlation – either positive or negative

-- Represented by +1 and -1

2. Some degree of correlation (positive or negative)

-- Represented by + .01 t + .99 and - .01 to -.99

3. No correlation

-- Represented by 0

Perfect Positive Correlation

Some Positive Correlation

Some Negative Correlation

Perfect Negative Correlation

No Correlation

Below is a guide in interpreting coefficients of correlation

-1

-75

-1

-1

-1

-1

-1

-1

-1

Perfect negative correlationVery high negative correlation

High negative correlation

Moderately negative correlation

Perfect negative correlation

Perfect negative correlationPerfect negative correlation

Perfect negative correlation

Perfect negative correlation

Perfect negative correlation

Perfect negative correlation