Strategic StudentIs this difference real?
You saw a number move. Maybe chronic absence dropped five points, or one group is outscoring another. Before you call it progress or a problem, check whether the difference is big enough to trust, or small enough to be chance. No PII. No login. Everything runs in your browser.
Enter the two numbers you're comparing
No PIIYour read will appear here
Enter a rate and a group size for each side above. We'll tell you whether the difference is statistically real or likely just noise.
How big the difference really is
The shaded band is the range the true difference most likely falls in. If it touches the center line, we cannot rule out no difference.
Keep in mind
How this works
This tool runs a two-proportion z-test, the standard way to ask whether two rates differ by more than chance. It compares the gap between your two rates to how much each rate could wobble given the number of students behind it, then reports a 95% confidence interval for the true difference.
A result is flagged "likely real" when it would happen by chance less than 5% of the time (p < 0.05), the common bar in education research. Small groups make almost any difference look like it could be chance, which is exactly why group size matters as much as the gap.
Statistical significance is not the same as importance. A tiny gap can be "real" with huge groups, and a meaningful gap can be "uncertain" with small ones. Always read it alongside what you know about your students. Source: standard two-proportion inference, see UConn, Confidence Intervals and Levels.
A significance test tells you a difference is probably not a fluke. It will never tell you it matters for a student. Use it to decide what is worth a closer look, then bring your judgment.