The Effects of Data Structure on Total Time on Test Plots.

Abstract : This research describes the effects data structure has on the Total Time on Test Transform technique and the resulting interpretation of the plot. Specifically, actual failure data on three card types (SUQ, BQQ, and BTJ) located in the Minuteman III Missile Guidance System was analyzed after manipulation. The manipulation consisted of the following three steps: 1) assign all zero time to failure values to the lowest failure time other than zero; 2) delete the zero time to failure values; and 3) delete all unusually high values from the sample data. After each step, the data was calculated and analyzed using Zenith 100 computer programs which performed the total time on test calculations and graphed those calculations into a total time on test data plot. The results of this analysis indicated that data structure does influence total time on test plots. The deletion of the zero time to failure values causes a movement upward of the data plot which could 1) decrease the indication of decreasing failure rate (DFR), 2) increase or decrease the number of crossings on the 45 degree line, and 3) increase the indication of increasing failure rate (IFR).