The "Critical T-Value" or t-test is defined as the statistical test that examines whether the test statistic follows the normal (Student's or bell curve) distribution, if the null hypothesis is true. The critical T-value may be calculated online using a freely available, web-based Critical Value calculator posted for faculty use by Vassar College. The tool allows the user to enter the number of groups in the distribution, and the number of degrees of freedom to produce the critical t-value at the .05 and .01 confidence levels for a given sample distribution. Other online tools (See Resources) assist the researcher in determining the effect size and in calculating degrees of freedom for the given sample distribution.

- Skill level:
- Easy

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### Things you need

- Degrees of Freedom known
- Number of groups in distribution

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## Instructions

- 1
Go to to the Vassar Calculator for the Critical Value of Q website (See Resources).

- 2
Type the number of groups in the distribution for the value of 'k'.

- 3
Type the degrees of freedom for the value of "df".

- 4
Click the "Calculate" button. The calculator will provide the two values of "Q": Q.05 and Q.01 as the Critical T-Value for the distribution at the .05 and .01 confidence levels, respectively.