Vose Three-parameter Lifetime Distribution | Vose Software

Vose Three-parameter Lifetime Distribution

Format: Lifetime3

The Three-Parameter Lifetime distribution is a lifetime distribution used for reliability modeling with an instantaneous failure rate given by:


It is particularly useful to model lifetimes that are driven by a ‘bathtub’ instantaneous failure rate (hazard rate) as shown in the following figure:



The distribution is an interesting alternative to the Weibull distribution, which is the probability distribution most commonly used in reliability analysis. The Weibull distribution has the ability to model either an increasing or decreasing instantaneous failure rate, but not both.

The three-parameter lifetime distribution was first developed by the risk analyst, David Vose.

ModelRisk functions added to Microsoft Excel for the Vose Three-Parameter Lifetime distribution

VoseLifetime3 generates random values from this distribution for Monte Carlo simulation, or calculates a percentile if used with a U parameter.

VoseLifetime3Object constructs a distribution object for this distribution.

VoseLifetime3Prob returns the probability density or cumulative distribution function for this distribution.

VoseLifetime3Prob10 returns the log10 of the probability density or cumulative distribution function.

VoseLifetime3Fit generates values from this distribution fitted to data, or calculates a percentile from the fitted distribution

VoseLifetime3FitObject constructs a distribution object of this distribution fitted to data.

VoseLifetime3FitP returns the parameters of this distribution fitted to data.


Three-parameter Lifetime Distribution equations