# Warranty Data Analysis Dates Format Example

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This example appears in the Life Data Analysis Reference book.

Dates of Failure Warranty Analysis

Assume that a company has the following information for a product.

 Quantity In-Service Date In-Service 6316 1/1/2010 8447 2/1/2010 5892 3/1/2010 596 4/1/2010 996 5/1/2010 8977 6/1/2010 2578 7/1/2010 8318 8/1/2010 2667 9/1/2010 7452 10/1/2010 1533 11/1/2010 9393 12/1/2010 1966 1/1/2011 8960 2/1/2011 6341 3/1/2011 4005 4/1/2011 3784 5/1/2011 5426 6/1/2011 4958 7/1/2011 6981 8/1/2011

 Quantity Returned Date of Return Date In-Service 2 10/29/2010 10/1/2010 1 11/13/2010 10/1/2010 2 3/15/2011 10/1/2010 5 4/10/2011 10/1/2010 1 11/13/2010 11/1/2010 2 2/19/2011 11/1/2010 1 3/11/2011 11/1/2010 2 5/18/2011 11/1/2010 1 1/9/2011 12/1/2010 2 2/13/2011 12/1/2010 1 3/2/2011 12/1/2010 1 6/7/2011 12/1/2010 1 4/28/2011 1/1/2011 2 6/15/2011 1/1/2011 3 7/15/2011 1/1/2011 1 8/10/2011 2/1/2011 1 8/12/2011 2/1/2011 1 8/14/2011 2/1/2011

 Quantity In-Service Date In-Service 5000 9/1/2011 5000 10/1/2011 5000 11/1/2011 5000 12/1/2011 5000 1/1/2012

Using the given information to estimate the failure distribution of the product and forecast warranty returns.

Solution

Create a warranty analysis folio using the dates of failure format. Enter the data from the tables in the Sales, Returns and Future Sales sheets. On the control panel, click the Auto-Set button to automatically set the end date to the last day the warranty data were collected (September 14, 2011). Analyze the data using the 2P-Weibull distribution and RRX analysis method. The parameters are estimated to be beta = 1.315379 and eta = 102,381.486165.

The warranty folio automatically converts the warranty data into a format that can be used in a Weibull++ standard folio. To see this result, click anywhere within the Analysis Summary area of the control panel to open a report, as shown next (showing only the first 35 rows of data). In this example, rows 23 to 60 show the time-to-failure data that resulted from the conversion.

To generate a forecast, click the Forecast icon on the control panel. In the Forecast Setup window, set the forecast to start on September 2011 and set the number of forecast periods to 6. Set the increment (length of each period) to 1 Month, as shown next.

Click OK. A Forecast sheet will be created, with the predicted future returns. Note that the first forecast will start on September 15, 2011 because the end of observation period was set to September 14, 2011.

Click the Plot icon and choose the Expected Failures plot. The plot displays the predicted number of returns for each month, as shown next.