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# How to Find the T Critical Value on a TI-84 Calculator

When you conduct a t-test, you will get a test statistic as a result. To determine if the results of the t-test are statistically significant, you can compare the test statistic to aÂ TÂ critical value. If the absolute value of the test statistic is greater than the T critical value, then the results of the test are statistically significant.

To find the T critical value on a TI-84 calculator, we can use the following function:

invT(probability, v)

where:

• probability: the significance level
• v: the degrees of freedom

You can access this function onÂ a TI-84 calculator by pressingÂ 2ndÂ and then pressingÂ vars. This will take you to aÂ DISTRÂ screen where you can then useÂ invT():

This tutorial shares several examples of how to use the invT() function to find T critical values on a TI-84 calculator.

### Example 1: T Critical Value for a Left-Tailed Test

Question:Â Find the T critical value for a left-tailed test with a significance level of 0.05 and degrees of freedom = 11.

Interpretation:Â If the test statistic of the t-test is less thanÂ -1.7959, then the results of the test are statistically significant atÂ Î± = 0.05.

### Example 2: T Critical Value for a Right-Tailed Test

Question:Â Find the T critical value for a right-tailed test with a significance level of 0.05 and degrees of freedom = 24.