If you have uncensored or arbitrarily censored data and no distribution fits your data, the Nonparametric Distribution Analysis can be used to estimate cumulative failure probabilities, hazard rates and draw survival, cumulative failure and hazard plots.
At the Excel Menu (For Excel 2007, go to Add-ins first)
Choose ProcessMA > Reliability and Survival > Distribution Analysis (Arbitrary Censoring) > Nonparametric Distribution Analysis
In Start, select the column containing start times (Numeric, Use * to represent left-censored data)
In End, select the column containing end times (Numeric, Use * to represent right-censored data)
In Frequency, select the column containing frequency counts (Optional, Positive integer)
Under Estimate Tab, in Confidence Level, enter the desired confidence level (Numeric, >0 & <1)
Under Graph Tab, check Survival Plot, if you want to display survival plot
Under Graph Tab, check Cumulative Failure Plot, if you want to display cumulative failure plot
Under Graph Tab, check Show Confidence Interval, if you want to display confidence interval in the above plots
Click OK
You work in a manufacturing plant making widgets and you want to find out the times at which widgets will fail. You have inspected the widgets at regular times (every 100 hours) to see how many have failed.
Open data worksheet by choosing ProcessMA > Tools > Data
Choose ProcessMA > Reliability and Survival > Distribution Analysis (Arbitrary Censoring) > Nonparametric Distribution Analysis
In Start, select CF - Start
In End, select CG - End
In Frequency, select CH - Frequency
Click OK
From the Turnbull Estimates table, 13.58% of widgets are estimated to fail between 500 to 600 hours. From the survival probabilities, 94.3% of widgets are estimated to survive until 300 hours.
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