Paired Mean Confidence Interval
Calculate a two-sided 95% t interval from the mean and SD of within-pair differences.
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Calculate a two-sided 95% t interval from the mean and SD of within-pair differences. All default values are fictional.
Calculation results
Mean difference: 2; 95% t interval: -0.0638986 to 4.0639.
SE: 1; degrees of freedom: 24; critical t: 2.0639.
Assumptions and limits
SE = SD(differences)/sqrt(n); 95% interval = mean difference ± t(0.975,n−1) SE. Enter the sample SD of within-pair differences, not a marginal SD or an SE. Pairs must be independent of other pairs; differences are normally distributed for exact small-sample inference. Assess outliers and distribution shape; a large sample does not repair dependence or selection bias. Define the direction and units before calculation. Complete pairs may not represent all enrolled participants. The interval does not establish causality or individual change. Positive SD required; supported n is 2–1 million.
NIST mean confidence interval · Read the practical guide · Download blank worksheet (TXT)