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lfiondella / SRT

Software Reliabilty Testing
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DSS Time to Target Reliability Inconsistent with Reliability Growth Plot #70

Closed a1729nikora closed 8 years ago

a1729nikora commented 8 years ago

On tab 4, the time to achieve a target reliability for the DSS model seems to be inconsistent with what I see on the reliability growth plot on Tab 3. For example, if I open the data set SYS1 in the model_data.xlsx workbook, subset the data to remove the first 20 failures, apply the DSS model, and plot the reliability growth for a 500 time-units mission, the reliability at the end observation in the data set is .9499, and a little time appears to be required to achieve a reliability goal of 0.96. On Tab 4, by contract, the query for a 500 time-unit mission to achieve a 0.96 reliability goal indicates that the goal has already been achieved.

The other models seem to behave correctly, so I'll start by looking at the equations to be solved in the DSS model.

a1729nikora commented 8 years ago

Corrected root_equation in function “DSS_R_MLE_root” in "DSS_BM_FT.R". Results are now consistent with reliability growth plot.