# Glossary “B” Definition of Terms in DataMyte

## β (beta) Risk

The maximum probability that a bad lot will be accepted by the sampling plan.

See also Consumer’s Risk.

## Bayes Theorem

A theorem of statistics relating conditional probabilities: Suppose that P(Ai IBj ) is the probability that A=Ai given that B = Bj , and suppose P(Bn) is the probability that B = Bn, where Bn is any outcome other than Bj . Then if we know that A = Am, then P(Bn) is given by the formula. The theorem is used for determining the probability P(BnIAm) when we have knowledge of the conditional probability P(AIB).

## Bell-shaped Curve

A curve or distribution showing a central peak and tapering off smoothly and symmetrically to tails on either side. A normal (Gaussian) curve is an example.

## Bias (in measurement)

Systematic error which leads to a difference between the average result of a population of measurements and the true, accepted value of the quantity being measured.

## Bimodal Distribution

A frequency distribution which has two peaks. Usually, an indication of samples from two processes incorrectly analyzed as a single process.

## Binomial Distribution (probability distribution)

Given that a trial can have only two possible outcomes (yes/no, pass/fail, heads/tails), of which one outcome has probability p and the other probability q (p + q = 1), the probability that the outcome represented by p occurs r times in n trials is given by the binomial distribution.