Two sample Z test

This macro performs a 2-sample Z test on either stacked or unstacked data stored in the active worksheet. The main difference between this test and a two sample t test is that the population standard deviations are assumed to be known for the 2-sample Z test.

Download the Macro

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Important

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Download TwoZTest.mac

Required Inputs

Either two columns of sample data (unstacked) or a single column of sample data and a corresponding column of group indicators (stacked)
The standard deviation for each group

Optional Inputs

ALPHA K: Use to specify an alpha level (K) other than the default of 0.05.
ALT K: Use to specify an upper or lower-tailed test instead of the default (Ho: mu1 - mu2 = 0). Use 1 as the argument for an upper-tailed test, -1 for a lower-tailed test.
DIFF K: Use to specify a test difference other than the default of 0.

Running the Macro

Suppose the data are unstacked and stored in C1 and C2 where the standard deviation for the first sample is 1 and for the second sample is 1.25.To run the macro, choose View > Command Line/History and type:

%TWOZTEST C1 C2 1 1.25

Click Run.

Suppose the data are stacked with the sample data in C1 and the group id's in C2, where the standard deviation for the first sample is 1 and for the second sample is 1.25.To run the macro, choose View > Command Line/History and type:

%TWOZTEST C1 1 1.25;
GRP C2.

Click Run.