Mathematical Methods · confidence intervals · manipulative

Confidence interval for a proportion

Unlike a mean CI with fixed σ, E = z√(p̂(1−p̂)/n) is widest at p̂ = ½ and collapses when p̂ is near 0 or 1.

Interval around p̂

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

Confidence level

95%

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

0.50
100

Working