Determination of the Critical Correlation Coefficient to Establish a Good Fit for Weibull and Log-Normal Failure Distributions

Least-squares rank regression is often used for curve fitting Weibull or Normal failure data. Most software packages calculate the correlation coefficient, r, or the coefficient of determination, r². Monte Carlo simulation was used to create and analyze several thousand data sets. By comparing r from a given sample to results obtained from Monte Carlo simulation, the goodness of fit of the sample can be determined.