Syntax
BETAINV(probability, alpha, beta, [A], [B])
| Parameter | Description |
|---|---|
| probability | Parameter of the BETAINV function. |
| alpha | Parameter of the BETAINV function. |
| beta | Parameter of the BETAINV function. |
| [A] | (Optional.) Parameter of the BETAINV function. |
| [B] | (Optional.) Parameter of the BETAINV function. |
Examples
95th percentile proportion
Formula
=BETAINV(0.95, 4, 16)
Returns ~0.3611. 95% of the beta distribution with alpha=4 and beta=16 falls below about 0.36.
Bounded percentile
Formula
=BETAINV(0.5, 2, 2, 0, 100)
Returns 50. A symmetric beta distribution (alpha=beta=2) mapped to [0,100] has its median at exactly 50.
Conservative rate estimate
Formula
=BETAINV(0.10, 6, 44)
Returns ~0.0764. The 10th percentile of the rate estimate is about 7.6% — a conservative lower bound.
Common Errors
#NUM!
Probability must be between 0 and 1 (inclusive). Alpha and beta must be positive.
#VALUE!
Occurs when arguments are non-numeric.
Tips
Use BETA.INV instead
BETAINV is the compatibility function. BETA.INV is the modern replacement with identical behavior.
Default bounds are 0 and 1
If you omit A and B, the function assumes the standard beta distribution on [0,1]. Specify A and B to work with variables on different scales.
Bayesian interpretation
In Bayesian analysis with a uniform prior, after observing s successes and f failures, BETAINV(p, s+1, f+1) gives the p-th quantile of the posterior for the true success probability.
Try BETAINV in Viztab
Import your data and use BETAINV with 370+ other formulas. No signup required.
Open Viztab