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Tolerance Allocation¶

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QXL Monte Carlo New > Monte Carlo > Contribution Tools > Tolerance Allocation...

Sweeps the spread of each input in turn and reports what happens to the outputs, so the report shows how much each input's variation matters to the defect rate.

The window states the shape of the run:

Every input whose spread can be swept is run at seven spread levels, and each level is one full Monte Carlo simulation. Nothing on this screen is saved to the model.

Seven levels per input¶

You give three percentages. Each is applied as plus and minus, which with the input's own unchanged spread makes seven levels: minus the largest, minus the middle, minus the smallest, unchanged, plus the smallest, plus the middle, plus the largest.

The cost is seven simulations per swept input. A model with eight swept inputs at 100,000 simulations a level is fifty-six full simulations.

Which inputs are swept¶

Only inputs whose spread can be swept. The report says for every input whether it was varied and, when it was not, why not.

Nothing here computes a result¶

Every level multiplier, defect rate and invalid-simulation count in the report is the engine's. The sweep runs through the ordinary Monte Carlo path and adds no evaluation mode of its own: the engine picks Fast Mode or Native Mode once for the whole sweep, exactly as it does for Run Model.

A second run lands beside the first¶

The report always asks for a worksheet named Tolerance Allocation, and Excel makes the name unique when one already exists, so a second run gives you Tolerance Allocation (2). Nothing is deleted, cleared or reused, so two runs can be compared side by side.

While it runs¶

A progress display shows how far through the sweep it is, and you can cancel it.

Options, for the sampling method, the count, the three percentages and the seed.
Percent Contribution, which answers a related question by decomposing variance rather than by sweeping spreads.