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Choosing a correlation test

Explanations > Social ResearchAnalysis > Choosing a correlation test

Choosing the test

Use the table below to choose the test. See below for further details.

How many dichotomous+ (binary) variables?

0

Both variables interval or ratio?

Y

 Measures are linear? (No = monotonic*) Y Pearson correlation N Spearman correlation

N

Both variables are ordinal?

Y

Kendall correlation

N

 Both variables can be ranked? Y Kendall correlation N Convert to frequency data and use Chi-square test for independence

1

Biserial Correlation Coefficient
2
 2 x 2 table? Y Phi N Cramer's V

 Data has frequency values for each category? Y Chi-square test for independence

+
dichotomous = 'can have only two values' (eg. yes/no or 0/1).
*monotonic = constantly increasing or decreasing.

Discussion

A correlation coefficient is measured between -1 and 1.

A positive indicates that if one variable increases, the other increases also. A negative coefficient indicates that if one variable increases, the other decreases.

0 indicates no relationship between the two variables.

1 or -1 indicates a linear relationships, such that if one variable is known, the second can be accurately predicted.

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