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Plots

Plot Setup

ALTA Plots

ALTA includes multiple plot types you can use to visualize the results of your accelerated life testing data analysis. You can create plots by choosing ALTA > Analysis > Plot or by clicking the icon on the Main page of the control panel.

Note that clicking the Plot icon before the parameters have been calculated will automatically calculate the parameters and then plot the data. The scaling, setup, exporting and confidence bounds settings are similar to the options available for all other plot sheets. (See Plots.)

Tip: ALTA includes two additional plots you could use across all types of data folios: the overlay plot, which allows you to compare different data sets; and the side-by-side plot, which allows you to simultaneously view multiple plots of one data set in a single window.

The following is a description of the different types of plots that can be created in an ALTA standard folio. Note that the use stress level for plots is by default the level you entered on the Main page of the control panel. However, you may adjust the level for plots by clicking Set Use Stress directly underneath the Analysis Summary area of the Plot page. This will not change the use stress level specified on the Main page.

If a model that uses the Weibull distribution is selected, an eta line will be displayed as well. The eta line estimates the time by which 63.2% of units in the population are expected to fail. The plot may also include other life lines that show the relationship between stress level and the time by which other specified percentages of a population are expected to fail (see Specifying Life Lines.) The life-stress relationship is linearized whenever possible.

For example, the next figures show the results of an Arrhenius-Weibull model and an Arrhenius-lognormal model using the same data set. As you can see, the plot shows that the lognormal distribution presents the better fit to this particular data set.

 

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