
DUANE PLOTName:
The Duane plot is used to assess whether or not cumulative failure times can be adequately modeled with a NonHomogeneous Poisson Process (NHPP)  Power Law model. If you have internet access, you can see a discussion of the NHPP Power Law model by entering the command:
Duane plots are generally preceeded by one or more of the following plots to check for trends in the repair rates:
If the trend plots do in fact indicate a trend, then the Duane plot should be generated. If the Duane plot shows a linear pattern, then this indicates that the NHPP Power Law model is consistent with the data. You do not need to specify XLOGON or YLOG ON as Dataplot does this automatically. Dataplot also resets the original values for these switches after the Duane plot is completed. A line is fit to the plotted data. Various parameters from the fit are saved as internal parameters. Specifically,
DPA1  slope of the fitted line DPCC  correlation coefficent of the fitted line SDDPA0  standard deviation of the intercept term SDDPA1  standard deviation of the slope term DPRESSD  residual standard deviation of the fitted line DPRESDF  degrees of freedom of the fitted line These can be used to assess the linearity of the Duane plot and can also be used to label the Duane plot (see the program example below).
where <y> is a response variable containing failure times; and where the <SUBSET/EXCEPT/FOR qualification> is optional.
DUANE PLOT Y1 SUBSET TAG > 1
 
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Date created: 6/5/2001 