Defects on the Market
The measure of system performance used in this study is the quality of the product at its launch date measured as the fraction of its constituent tasks that are defective. When the launch date is reached, all tasks in the
Current Work Sector are launched regardless of level of completion or testing. These unfinished, untested tasks are the source of defects on the market.The Fraction Defective at Launch is calculated first by summing all the defects introduced into the market by the launch flows. Then the sum is divided by the total launch flows. (The sum of all the launch flows is equal to the original task introduction flow into the Current Work Sector.) This will give us an instantaneous fraction of the overall defects in the market.
(078) Frac Defective at Launch= ZIDZ( Curr Tasks in Rework Launched *Defects Per Task Failing Test +Curr Tasks Not Comp Launched *Defects Per Task Failing Test +Curr Tasks Comp Launched *Defects Per Task Passing Test +Curr Task in Testing Launched *Fraction of Curr Tasks Defective *Defects Per Task Failing Test, Curr Tasks Comp Launched +Curr Task in Testing Launched +Curr Tasks in Rework Launched +Curr Tasks Not Comp Launched)
Units: defects/task
Fraction of Tasks Introduced to the Market that are Defective. This is the sum of the defects introduced by the launch flows divided by the total launch flows. Here, the launch flows that contribute to the defects on the market are Current Tasks not Completed and Current Tasks in Rework. These are assumed to be fully defective. For Current Tasks in Testing, only the "Fraction of Current Tasks Defective" has defects. The launch flow from Current Tasks Completed is assumed to be defect-free.
(066) Defects Per Task Failing Test=1
Units: defects/task
The corresponding defects per each task failing test. The value 1 means that there is one defect per task that fails testing.
(067) Defects Per Task Passing Test=0
Units: defects/task
The corresponding defects per each task passing test. The value 0 means that there is no defects per task that passes testing.
Here, the launch flows that contribute to the defects on the market are Current Tasks not Completed and Current Tasks in Rework. These are assumed to be fully defective. For Current Tasks in Testing, only the "Fraction of Current Tasks Defective", from the
Current Defects Sector, has defects. The launch flow from Current Tasks Completed is assumed to be defect-free.The information of defect fraction at Launch is then kept in a memory stock, called the "Fraction defective for Launched Model". This stock remembers the information until the next launch.
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Overview | Advanced Work | Current Work | Current Defects | Market Defects | Capacity Allocation |