Ztesti

Ztesti is a term that may refer to a statistical testing tool or library focused on z-tests. There is no single, formally recognized definition of ztesti in major statistical reference literature, and the term can appear as the name of a small project, a function set within a broader package, or as a colloquial shorthand in tutorials.

In statistics, a z-test assesses whether a sample statistic differs significantly from a known population parameter, using the standard normal distribution. Z-tests are typically used when the population variance is known or when sample sizes are large. Common variants include the one-sample z-test, the two-sample z-test, and tests for proportions.

A hypothetical tool named ztesti would typically provide functions to compute the z-statistic, the corresponding p-value, and confidence intervals. It would support both known and large-sample variance assumptions, offer vectorized input, accept data frames or arrays, and return structured results with clear labeling of statistics, p-values, and effect sizes.

Practical usage centers on hypothesis testing for mean differences or proportion differences under normal-theory assumptions. Limitations include sensitivity to incorrect variance assumptions and inadequacy for small samples where the z-test is not appropriate; in such cases, alternatives like the t-test are preferred.

Overall, ztesti functions would align with standard z-test methodology and may serve as a convenience wrapper within statistical workflows, subject to the same interpretation rules as other z-tests.