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This test is used for large samples to test the hypothesis:
H0: the proportion is the same in both populations
H1: the proportions are different/the proportion is greater for process 1 than process 2
The value of the Z statistic is calculated from:
where:
p1 and p2: the proportions in each sample
X1 and X2: the number possessing the characteristic in each sample
n1 and n2: the sample size
The p-value can be obtained from Excel using the function:
one-tail test: = 1 - NORMSDIST(Z0)
two-tail test: = (1 - NORMSDIST(Z0))/2
Alternatively the critical values can be found in the t-tables.
| Hypothesis Test for Proportions |
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For large samples, refer to the tests "Comparing Proportions" and "Proportions Against a Specified Value". For small sample sizes refer to Chi-Square tests.
| Proportion Against a Specified Value |
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This test is used for large samples to test the hypothesis:
H0: the proportion is the same in both populations
H1: the proportion is [different to/greater than/less than] the specified value
The value of the Z statistic is calculated from:
 the proportion in the sample
 the specified value of the proportion
n the sample size
The p-value can be obtained from Excel using the function:
one-tail test: = 1 - NORMSDIST(Z0)
two-tail test: = (1 - NORMSDIST(Z0))/2
Alternatively the critical values can be found in the t-tables.
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