Reliability HotWire

Issue 87, May 2008

Tool Tips

* How can I exclude effects from my DOE++ analysis?
There may be effects of factors or factorial interactions that you wish to exclude from your Design of Experiments (DOE) analysis, based either upon prior knowledge or upon initial analysis. To do this in DOE++, select Select Effects from the Data menu or click the Select Effects icon in the Design tab or Analysis tab Control Panel.

In the Effects window, you can specify for each response which main effects and interaction effects you want to include in the model.

To make changes for the response currently selected in the Response drop-down, you can:

Select or clear individual checkboxes to include/exclude individual effects.
Select or clear the checkbox in the Effect Name header to include/exclude all effects.

OR

Use the Limit by Order drop-down to specify the order of effects you want to include in the model.

For example, if you select "Main Effects," only the individual effects of the factors (e.g. A, B, C...) will be included. If you select "Order 3 Effects," the model will include the main effects, the second order effects (e.g. AB, AC, BC...) and the third order effects (e.g. ABC...). The options available in this drop-down menu will vary depending on the design and the number of factors. Response surface method designs allow you to choose among linear, interaction and/or quadratic effects. You can apply your changes to all responses instead of just the one currently selected by clicking the Apply to All Responses button.

Note, however, that when the Effects window is accessed from the Analysis tab, the choices you make will be applied only to the response currently selected in the Control Panel. The Response drop-down menu and the Apply to All Responses button will be disabled.

* How can I display probability scales on the probability plots in Weibull++ 7? 
Probability scales allow the user to read parameter estimate values directly from the probability plot. In Weibull++ 7, the probability scales are toggled on and off in the Show/Hide Plot Items window, which is accessed by selecting Show/Hide Items from the Plot menu or the shortcut menu that appears when you right-click inside the plot area.

The appearance of the probability scales can be changed on the Lines page of the Plot Setup window, which is accessed by selecting Plot Setup from the Plot menu or shortcut menu or by clicking the Plot Setup icon.

In the Name field on the Lines page, select Other from the first drop-down and then Probability Scales from the second drop-down, as shown next.

In the Show area, you can select whether to show the scales and/or the bars for the probability scales. You can specify the color, thickness and style for the probability scale lines and the color and pattern of the fill for the probability scale bars using the options on this page.

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