COCHRAN Subcommand (NPAR TESTS command)

NPAR TESTS COCHRAN=varlist

COCHRAN calculates Cochran’s Q, which tests whether the distribution of values is the same for k related dichotomous variables. The output shows the frequency distribution for each variable in the Cochran Frequencies table and the number of cases, Cochran’s Q, degrees of freedom, and probability in the Test Statistics table.

Syntax

• The minimum specification is a list of two variables.
• The variables must be dichotomous and must be coded with the same two values.

Operations

• A k × 2 contingency table (variables by categories) is constructed for dichotomous variables, and the proportions for each variable are computed. A single test is calculated, comparing all variables.
• Cochran’s Q statistic has approximately a chi-square distribution.

Example

NPAR TESTS COCHRAN=RV1 TO RV3.

• This example tests whether the distribution of values 0 and 1 for RV1, RV2, and RV3 is the same.