# 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 H_{0} 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 (n_{numerator} - 1) and the denominator degrees of freedom (n_{denominator} - 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.