Statistics for Maintenance Modelling: Continuous Lifetime Distributions 2

# The Hazard Function for the Lognormal Distribution¤

Again there is no analytical expression for the hazard function. Furthermore the hazard function is no longer monotonic but is peaked as is shown below and is zero for t = 0 and t = . In practice it is unusual to meet a decreasing hazard function for large t, and so this is a drawback of the lognormal distribution. However it is sometimes used when large t values are of no interest, i.e. the region to the left of the hazard function's peak is all that is of interest.

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