# Statistical test functions

Statistical test functions can be used in both the data load scriptand chart expressions, but the syntax differs.

## Chi-2 test functions

Generally used in the study of qualitative variables. One can compare observed frequencies in a one-way frequency table with expected frequencies, or study the connection between two variables in a contingency table.

## T-test functions

T-test functions are used for statistical examination of two population means. A two-sample t-test examines whether two samples are different and is commonly used when two normal distributions have unknown variances and when an experiment uses a small sample size.

## Z-test functions

A statistical examination of two population means. A two sample z-test examines whether two samples are different and is commonly used when two normal distributions have known variances and when an experiment uses a large sample size.