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Two Sample Z Test Calculator
Compare two means with known population standard deviations using a z test.
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Compare two means with known population standard deviations using a z test.
Two Sample Z Test Estimator
Enter your numbers below for an instant estimate.
0
๐ก Tip: z = (m1 – m2) / sqrt(s1^2/n1 + s2^2/n2).
How It Works
Key concepts behind this calculator
1
Enter Values
Fill in each field with your own numbers.
2
Calculate
Results update as you change the inputs.
3
Review
Read the breakdown and the explanation.
4
Adjust
Change values to compare scenarios.
Quick Reference Guide
Two Quick Guide
Typical values for reference.
| Means | SDs | Sizes | Result |
|---|---|---|---|
| 105 vs 100 | 15/14 | n 50/60 | z 1.79, p 0.0728 |
| 110 vs 100 | 15/15 | n 40/40 | z 2.98, p 0.0029 |
| 52 vs 50 | 10/10 | n 100/100 | z 1.41, p 0.1573 |
| 20 vs 18 | 4/4 | n 25/30 | z 1.85, p 0.0648 |
| Rule of Thumb | Check inputs | Use as a guide | Round sensibly |
Common Questions
Two Sample Z Calculator FAQ
Answers to common questions about this calculator.
When population standard deviations are known or samples are large.
The spread of the difference between means.
A range of plausible values for the true difference.
The t test estimates sigma from the data.