Tools

Z-Test

Calculator

  Population Sample
Mean
Standard deviation  
Sample size  
Alpha  
Tail / side

Result


Fill in the fields in the calculator box and press 'Calculate' for the statistical significance.

Calculator

  Sample 1 Sample 2
Mean
Standard deviation
Sample size
Alpha  
Tail / side

Result


Fill in the fields in the calculator box and press 'Calculate' for the statistical significance.

Calculator

  Sample 1 Sample 2
Proportion
Sample size  
Alpha  
Tail / side

Result

Calculator

  Sample 1 Sample 2
Proportion
Sample size
Alpha  
Variance
Tail / side

Result

Calculator

z-score z-score to p-value
p-value p-value to z-score
Tail / side

Result


Fill in the fields in the calculator box and press 'Calculate' for the statistical significance.


Information

A z-test is used to test the location of a sample mean in respect to a given mean (one-sample z-test) or another sample (two-sample z-test). The z-test is employed when the sample size is large and the data is assumed to come from a normal population of which the variance is known. If the variance of the population is unknown, a t-test should be used.

The second application of the z-test is the assessment of proportions. The z-test calculator for proportions is used to investigate whether two populations differ significantly in proportion – for example, whether there is a difference in the proportions of two groups that went voting for the last election.

To use these online z-test calculators, fill in means or proportions, the standard deviation, and/or the sample size. Alpha is used to determine the maximum error level (default is 0.05) and has to be between 0 and 1. The tail options let you decide whether you want to perform a one-sided test (left or right) or a two-sided test (both).


Example of one-sample z-test

Tested is whether the math score of 60 students from a particular school is lower as compared with the average reading score in that region. The regional average and standard deviation of math scores are 100 and 15 points, respectively. The 60 students that are under investigation have a mean score of 96 points. The resulting z-score is -2.0656.