Unequal-variance mean contrast
Compute the unpooled standard error and Welch–Satterthwaite degrees of freedom.
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Enter exactly two rows: mean, sample SD and sample size. Sample sizes must be whole numbers of at least two. The output difference is first-row mean minus second-row mean. The SE is in the outcome's units; fractional degrees of freedom are intentional. No confidence interval or p-value is returned.
The starting values are hypothetical. Results update as you edit. Use aggregate or synthetic inputs only.
Calculation results
- Difference, first minus second
- 2
- Standard error
- 2
- Welch degrees of freedom
- 5.8823529
How to interpret the output
Compare independent group means in the same units. Variance of the difference is s1²/n1+s2²/n2. Fractional degrees of freedom approximate the sampling distribution. This summary cannot assess skew, sampling bias or clustering.
Method reference