BEAST 2 Help Me Choose

BEAST 2 Help Me Choose Beta beta

Beta distribution – beta

Second shape parameter, defaults to 1.

The parameter beta can be interpreted as the number of times (plus one) a one has been observed, so setting beta to one means no observations, beta=4 means 3 observations. Likewise, the parameter alpha can be interpreted as the number of times (plus one) a zero has been observed.

If both alpha and beta shape parameters are 1, the Beta distribution becomes a uniform distribution.

Values of alpha and beta less than 1 lead to distributions that are highly skewed towards 0 and 1.

Values of alpha and beta more than 1 lead to distributions that have mean alpha/(alpha+beta) and zero density at 0 and 1.