Related Topics:
	Warranty Analysis Folios

Warranty Analysis Plots

You can plot the data in the warranty analysis folio either with or without generating a forecast. The features on the plot sheet are similar to the options available for all other Weibull++ plots. Features that are not applicable to warranty analysis will be hidden or disabled.

In addition to the standard plots in Weibull++, the following plot types are available for warranty analysis:

• Expected Failures plot shows the expected number of failures over a period of time. This plot is available for all warranty data formats. Four additional options in the control panel are associated with this plot:

• • Cumulative Failures shows the cumulative percentage of failures for each time period. For example, consider 10 units that had failed within a period of 6 months. If 2 units failed during the 1st month, then the percentage of failures is 2/10 = 20%. If 3 more units failed during the 2nd month, then the cumulative percentage of failures is (2+3)/10 = 50%, and so on.

  • Failures in Percents shows the failures as percentages of the total number of units originally in-service. Otherwise, the failures will be plotted as raw numbers.

  • Show Confidence Bounds shows the upper and lower confidence bounds on the plot.

  • Include Total Data is available only when the Use Subsets check box was selected on the Main page of the control panel. It shows a plot of the entire data set, along with the selected subsets. This allows you to view the overall trend of the entire data set in addition to the trends exhibited by each subset of data.

• Chi-Squared Sales and Chi-Squared Returns plot types are available only when using the statistical process control (SPC) feature of the Nevada chart format. These plots give a visual indication of whether the expected number of warranty returns for a certain period is within or outside an expected range.