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# How to Find the Z Critical Value in Excel

Whenever you conduct a hypothesis test, you will get a test statistic as a result.Â To determine if the results of the hypothesis test are statistically significant, you can compare the test statistic to aÂ Z critical value.

If the absolute value of the test statistic is greater than the Z critical value, then the results of the test are statistically significant.

Fortunately, Excel makes it easy to find Z critical values using the following function:

NORM.S.INV(probability)

where:

• probability:Â The significance level to use.

This function returns a Z critical value, based on the significance level you chose.

This tutorial provides three examples of how to use this function to find Z critical values.

### Example 1: Two-Tailed Test

Find the Z critical value for a two-tailed test, usingÂ Î± = 0.10.

For a two-tailed test, there will be two critical values:

• NORM.S.INV(Î±/2)
• NORM.S.INV(1-Î±/2)

We can use the following functions in Excel to calculate these critical values:

Thus, the two critical values for this test areÂ -1.645 andÂ 1.645. This means if the test statistic is less than -1.645 or greater than 1.645, then the results of the hypothesis test are statistically significant.

### Example 2: Right-Tailed Test

Find the Z critical value for a right-tailed test, usingÂ Î± = 0.05.

For a right-tailed test, there will be one critical value: NORM.S.INV(1-Î±)

We can use the following function in Excel to calculate this critical value:

Thus, the critical value for this test isÂ 1.645. This means if the test statistic is greater than 1.645, then the results of the hypothesis test are statistically significant.

### Example 3: Left-Tailed Test

Find the Z critical value for a left-tailed test, usingÂ Î± = 0.01.

For a left-tailed test, there will be one critical value: NORM.S.INV(Î±)

We can use the following function in Excel to calculate this critical value:

Thus, the critical value for this test isÂ -2.326. This means if the test statistic is less than -2.326, then the results of the hypothesis test are statistically significant.