Method 1 – Find T Critical Value in Excel
The T critical value is basically the indicator of determining the statistical significance of a T-test. Depending on the type of test, the calculation process varies.
1.1 Use T.INV Function for Left-Tailed Test
Steps:
- Go to C8. Write down the following formula.
=T.INV(C4,C5)
- Press ENTER. Excel will return the result.
1.2 Combine ABS and T.INV Functions for Right-Tailed Test
Calculate the T critical value for a right-tailed test. This time I will use the ABS function along with the T.INV function.
Steps:
- Go to C9. Write down the following formula.
=ABS(T.INV(C4,C5))
Explanation:
The T.INV(C4,C5) returns the T-value for the left-tailed test and the ABS function adjusts the result for a right-tailed one.
- Press ENTER. Excel will return the result.
1.3 Apply T.INV.2T Function for Two-Tailed Test
Focus on a two-tailed test. To calculate the T critical value for a two-tailed test, we ought to use the T.INV.2T function.
Steps:
- Go to C10. Write down the following formula
=T.INV.2T(C4,C5)
- Press ENTER. Excel will show the result.
Method 2 – Use of NORM.S.INV Function to Find Z Critical Value in Excel
Put some light on Z critical value. It is a statistical term widely used to determine the statistical significance of a hypothesis. The population parameters are of concern. We need to calculate the Z critical value for 3 different types of cases.
- Left-tailed test
- Right-tailed test
- Two-tailed test
2.1 For Left-Tailed Test
Steps:
- Go to C8 and write down the following formula
=NORM.S.INV(C4)
- Press ENTER. Excel will return the output.
2.2 For Right-Tailed Test
Steps:
- Go to C9 and write down the following formula
=NORM.S.INV(1-C4)
- Press ENTER. You will get the result.
2.3 For Two-Tailed Test
Steps:
- Go to C10. Write down the following formula
=NORM.S.INV(C4/2)
- Press ENTER to get the output.
- Write down the following formula in C11.
- Press ENTER to calculate the result.
Things to Remember
- The ABS function adjusts the T value for a right-tailed test.
- The T and Z critical values differ from the T and Z values. We calculate the T and Z values from the sample statistic and population parameters. Then we compare those values with the critical values to determine the statistical significance of a hypothesis.
- T values are used when the standard deviation of the population is unknown and the sample size is relatively small.
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