﻿Critical value calculator - Normal, t, F, and chi-square distributions.

# Critical Value Calculator

Calculates the critical value for the following: student's t-distribution, normal distribution, F distribution and chi square distribution

## Critical Value Calculator

### What is the critical value?

The critical value the boundary between the accepted region (green) and the rejected region (red). Under the assumption that the H0 is correct, the probability to get the critical value or more extreme value (red) is the significance level (α).
What is more extreme?
Two-tailed: two critical values, more extreame is smaller than the smaller critical value or larger than the larger critical value.
Left-tailed: smaller than the critical value.
Right-tailed: larger than the critical value.

### how to find critical value?

Calculate the score from the probability using the score calculator - enter probability or tables only if you have to If you use a one-tailed test the probability is the significance level (&alpha), and if you use a two-tailed test the probability is the significance level divided by 2 (α/2).

#### Left tailed test

The critical value will be negative for symmetrical distributions around zero, like normal distribution and t-distribution, But it can be positive for, like in the chi-squared distribution

• The critical probability is: α. For example 0.05
• Calculate the score of α. t-score or z-score or F-score etc.)

#### Right tailed test

Usually the critical value will be positive.

• The critical probability is: 1- α. For example 1 - 0.05 = 0.95
• Calculate the score of 1 - α
• The critical probability is: α. For example 0.05
• Calculate the score of α

### Z critical value calculator

The Z critical value calculator calculates the critical value for the z statistic (normal distribution), choose the normal distribution and enter the mean and standard deviation.
For a standard normal distribution enter μ = 0 and &sigma = 1.

### t critical value calculator

The t critical value calculator calculates the critical value for the t statistic, choose the Student's t distribution and enter the degrees of freedom (n - 1).

### F critical value calculator

The F critical value calculator calculates the critical value for the F statistic, choose the F distribution and enter the numerator degrees of freedom (nnumerator - 1) and the denominator degrees of freedom (ndenominator - 1).

### Chi square critical value calculator

The chi square critical value calculator calculates the critical value for the chi-squared statistic, choose the Chi-square distribution and enter and enter the degrees of freedom.