Hypothesis
Z Test for Differences in Two Population Proportions
This worksheet will calculate the sample z and critical z scores for the z test for the difference between
two population proportions. Edit the blue fields below to reflect values for the test you are conducting.
NOTE: the "number of successes" refers to the number of sampled observations that have the characteristic
that the sample proportion is being calculated for.
Data
Hypothesized difference between proportions 0
Level of significance for test 0.05
Group 1
Number of Successes 35
Sample Size 50
Group 2
Number of Successes 20
Sample Size 50
Intermediate Calculations
Group 1 sample proportion 0.7
Group 2 sample proportion 0.4
Difference in two sample proportions 0.3
Average proportion for two samples 0.55
sample Z test statistic 3.015113446
Two-Tailed Test
Critical z value 1.959963985
p -Value 0.002568832
Reject the null hypothesis
One-Tailed Test
Critical z value 1.644853627
p -Value 0.001284416
Reject the null hypothesis if the sample proportions agree with the alternative hypothesis
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Hypothesis
difference between
ou are conducting.
the characteristic
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