Free F-Statistic Calculator
Calculate the F-statistic as the ratio of two sample variances to test whether population variances are equal.
F-Statistic
1.562500
df1 (numerator)19
df2 (denominator)24
SD Ratio1.2500
F-Statistic vs Sample Variance 1 (larger)
How to Calculate the F-Statistic
Formula
F = s1^2 / s2^2
The F-statistic is the ratio of two sample variances, with the larger variance in the numerator by convention. Under the null hypothesis of equal population variances, F follows an F-distribution with df1 = n1-1 and df2 = n2-1. F-values near 1 suggest equal variances.
Example Calculation
Group 1: variance = 25, n = 20. Group 2: variance = 16, n = 25.
- 01F = 25 / 16 = 1.5625
- 02df1 = 20 - 1 = 19
- 03df2 = 25 - 1 = 24
- 04SD ratio = sqrt(1.5625) = 1.25
- 05Compare F = 1.5625 to F-distribution(19, 24)
Frequently Asked Questions
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