Statistical inference · confidence intervals · manipulative

Confidence interval for a mean

E = z·s/√n. Dial the sample mean and confidence level, and see why a larger sample sd s forces a wider interval.

Interval around x̄

How E depends on n (current z and s fixed)

Confidence level

level % 95%

Presets jump; the slider sets any whole-number level from 80% to 99%.

sample mean 50

sample size n 30

sample sd s 10

s is the sample standard deviation — how spread out the data are. Larger s ⇒ wider E.

Working