I'm pretty sure I'm seeking standard deviation and finding the mass of my 'widgets' that exist outside my SD. Here's the context.
I just sorted a bunch of widgets into two piles. One pile is known bad widgets and are being deconstructed. I want to quality control/quality assurance the other pile of widgets.
These widgets are made up of four distinct components, components a, b, c, and d. Three of said components are determinant and their mass will vary only slightly. For simplicity their mass is negligible thus of course the characteristics of every completed widget can vary only slightly piece to piece.
The differences between the masses of components a, b and c, should be negligible to the difference in component d; ie: a known good mass of component d should be 22.2 grams. Component a will almost always equal 55 grams +/- a few hundredths of a gram, the same goes for components b and c; and thus should remain relatively constant. The greatest difference in weight from widget to widget should be seen in component d.
If I can calculate the population mean of the mass then I can collect the standard deviation of the population.
For any widget that has a mass outside 1 or 2 standard deviations those widgets are candidates for deconstruction.
I think my logic is sound. I just need to do the math now. This means taking records of every widgets weight, finding the SD, and then using that to pull any anomalies out of the population.
Am I on the right track here? Or should I be considering some sort of distribution to help me judge what of my widgets I should be deconstructing?
Moderators, I'm not sure if this sort of question belongs here, or in Math. Please advise. Thank you.