Syntax: ZTEST(Range, X[, S])
Range = a range containing sample values
X = a value to be tested
S = (optional) the standard deviation of the sampled population, if known
ZTEST returns the Z-score for a two-tailed test of the hypothesis that X is the mean of the population from which the samples in Range are drawn. The population is assumed to be normally distributed with standard deviation S. If S is omitted, it is estimated from the sample values in Range. If S is given, it must be greater than 0.
The mathematical formulation is given as follows:
Let z =
, where is
the actual mean, N is the number of samples, and
is the standard deviation. Then,
Suppose A1..A10 contains the sample values 0.552, 5.090, 4.494, 7.833, 7.101, 0.590, 2.439, -3.197, 8.861, and -2.795.
ZTEST(A1..A10, 3) = 0.47151484
ZTEST(A1..A10, 3, 4) = 0.46949987
ZTEST(A1..A10, 3, 0) = Error
Excel function: ZTEST