TTEST - Returns the probability associated with a Student's t-Test in Excel

The following article details how to use the ZTEST function - The function to calculate the one-sided probability value of a z test.

Description: The function returns the one-sided probability value of the z test. For the hypothetical population mean, the function returns the probability that the sample mean will be greater than the sample mean observed in the data set or array.

Syntax: ZTEST (array, x, [sigma]) .

Inside:

- array : An array or range of data to test for x, which is a required parameter.

- x : Value to check, required parameters.

- sigma : The overall standard deviation, if omitted the default value is the sample standard deviation, is an arbitrary parameter.

Attention:

- If array array is empty -> the function returns the # N / A error value.

- ZTEST function is calculated based on the formula:

+ Where sigma is used:

+ In case of omitting sigma parameter:

- ZTEST function indicates that the probability that the sample mean will be greater than the observed value is AVERAGE (array) when the average of the basic population is μ0 => ZTEST will return a value greater than 0.5 when AVERAGE ( array) < μ0 .

- You can use the ZTEST function to calculate the probability of 2 sides based on the formula:

2 * MIN (ZTEST (array, μ0, sigma), 1 - ZTEST (array, μ0, sigma)) .

For example:

Step 1: In the cell to calculate enter the formula: = ZTEST (D6: I6, D7) .

Step 2: Press Enter -> ZTEST function value is:

In addition, you can also calculate the 2-sided probability based on the ZTEST function :

Step 1 : In the cell to calculate, enter the formula: = 2 * MIN (ZTEST (D6: I6, D7), 1-ZTEST (D6: I6, D7)) .

Step 2: Press Enter -> the value of the ZTEST function on both sides is:

Above is a detailed guide of meaning, usage and some notes when using ZTEST .

Good luck!