Reliability HotWire: eMagazine for the Reliability Professional
Reliability HotWire

Issue 63, May 2006

Tool Tips

* Tips on working with plots in Weibull++ and RENO
There are several additional commands that you can use when you are working with plots in either Weibull++ 7 or RENO.

To show the coordinates of any location on the plot, press Shift and click in the plot. A box displaying the coordinates of the selected location will appear, as shown next.

If the cursor is on a plot line (e.g. the probability line, confidence bounds, etc.), pressing Shift and clicking the line will track the line when you move the cursor. A crosshair will be displayed showing the current location on the line. As you move the cursor left or right, the crosshair will mirror the movement but will stay on the line and the current coordinates on the line will be displayed (i.e. Y is calculated based on X), as shown next.

Pressing Ctrl+Shift and clicking the line does the same thing, but X is calculated based on Y.

To add a custom label to the plot, press Ctrl and click in the plot. A new label will appear in the plot, as shown next.

Double-click the label to open the Edit Label window, where you can specify the text for the label. Clicking Set Font opens the Font window, which allows you to specify the font, size, style, color and orientation used for the label.

To add a label that displays coordinates to the plot, position the cursor at the location you want labeled then press Ctrl and Alt and click the location. A coordinate label will be added to the plot, as shown next.

Pressing Alt and clicking a plotted line or point will open a window allowing you to bring the line or group of points to the front or send it to the back, as shown next.

You can click any plot element (i.e. point, line, bar, slice or state) to open the Plot Setup window. The element you clicked is automatically selected on the last page of the Plot Setup.

Further details about the use of these commands is provided in each applications online help file and Users Guide.

* Can returns be allowed in the same periods as the sales periods?

When using the Nevada format of the Warranty Specialized folio, Weibull++ allows the user to enter failures that occur during the same period as the sales period. For example, consider a manufacturer that monitors monthly sales and returns. If 200 units were sold in May 2006 and 2 failures happened during the same month (or 2 units did not work immediately upon use), those units are considered to have times-to-failure of zero. This can be recorded by selecting the Allow Returns at Time = 0 in the Project Wizard of the Nevada warranty chart. If the option is not selected, all returns must occur in periods after the sales period. The 3-parameter Weibull, mixed Weibull, 2-parameter exponential and generalized gamma distributions cannot be used for data sets containing failure times of zero.


Note that if Allow Returns at Time = 0 is not selected, then failures entered at return periods equal to the sales period will be ignored in the analysis.

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