The sample data file, found in the Reliability subfolder, contains data on failures for a turbine engine design over three phases of a testing program. The first two columns give time intervals during which failures occurred. These intervals are recorded as days since the start of testing. The exact failure times are not known; it is known only that failures occurred within these intervals.
Select Help > Sample Data Library and open Reliability/
Select Analyze > Reliability and Survival > Reliability Growth.
On the Time to Event Format tab, select the columns Interval Start and Interval End, and click Time to Event.
Select Fixes and click Event Count.
Select Design Phase and click Phase.
The Cumulative Events plot from the Observed Data report is shown in Cumulative Events Plot. The vertical dashed blue lines indicate the phase transition points. The first occurrence of Revised in the column Design Phase is in row 14. So, the start of the Revised phase is taken to be the Interval Start value in row 14, namely, day 91. Similarly, the first occurrence of Final in the column Design Phase is in row 23. So, the start of the Final phase is taken to be the Interval Start value in row 23, namely, day 200.
Cumulative Events Plot
The Piecewise Weibull NHPP report is found under the Models outline node (MTBF Plot). Here we see the mean time between failures increasing over the three phases. From the Estimates report, we see that the estimates of beta decrease over the three testing phases.

Help created on 9/19/2017