Z-Tests
Statistics

Paired Samples Z-Test

This test evaluates whether two dependent samples represent populations with different means while using the known variances of the populations to calculate the z value.

The two samples must have the same number of data points, and must be matched as nearly as possible (e.g., carbon isotope values measured on two dependent samples, taken from a population whose variance is 0.86).

  • The data from two dependent samples should be stored in separate numeric columns.
  • The test report includes p (one-tailed) and p (two-tailed) (see the image below).

Unpaired Samples Z-Test

This test evaluates whether two independent samples represent populations with different means while using the known variances of the populations to calculate the z value.

The two samples can have the same or a different number of data points (e.g., porosity measurements on two independent sandstones with population variances of 6 and 5).

  • The data from independent samples should be stored in separate numeric columns.
  • The test report includes p (one-tailed) and p (two-tailed) (see the image below).