A TI-84 style calculator with 20+ functions — normal, t, χ², F, binomial, geometric, Poisson, and inference tests. Select a function from the DISTR menu on the screen.
Use -1E99 / 1E99 for ±∞ in cdf bounds. χ², t, and F shapes depend on degrees of freedom; as df→∞ all approach Normal.
z = (p̂ − p₀) / √(p₀(1−p₀)/n) — 1-Prop Z-test
z = (p̂₁−p̂₂) / √(p̂c(1−p̂c)(1/n₁+1/n₂)) — 2-Prop Z-test
t = (x̄ − μ₀) / (s/√n) — 1-Sample t-test
t = (x̄₁−x̄₂) / √(s₁²/n₁+s₂²/n₂) — 2-Sample t-test
F = s₁² / s₂² — F-test for equal variances (df₁=n₁−1, df₂=n₂−1)
Interactive critical-value and probability tables computed live. Use the lookup tools to highlight any value.
Reading: body = P(Z < z). Row = tenths, column = hundredths. Right-tail = 1 − value.
Reading: body = t* with given one-tail area. Header row = matching confidence level. Bottom row (df=∞) = z critical values.
Reading: body = χ²* with listed right-tail area. Used for goodness-of-fit, independence, and variance tests.
Reading: columns = df₁ (numerator), rows = df₂ (denominator). Body = F critical value at chosen right-tail α. Used for ANOVA and variance ratio tests.