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.

Sales

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

Returns

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

Future Sales

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.