Out-of-the-Box Part 2 - One Sample Mean Testing with Z.TEST
Previously we saw the One Sample Mean test implemented using LAMBDA by calculating the test statistics. Excel provides something similar using the Z.TEST function. The Z.TEST function compares the average of a sample if it is statistically less than or equal to a test value. The formula is stated as: Z.TEST(array, x, [sigma]) where array is the range of data to be tested against x x is the value of test. sigma is optional. If the population standard deviation is known, put it here. Otherwise leave it empty, and Excel will use the sample standard deviation instead. In effect you are testing to see if the average of the array is less than or equal to x `bar(array) < x` Comparing for Less Than or Equal To Observe the box plot of 5 sample distributions above. We want to check if the distributions averages are less than or equal to the value of 50 . We see samples A and B less than 50, sample C around 50, and samples D and E more than 50. NOTE: Where possible do box plots of the