# CHM242H5 Final: How to do Error Analysis For labs and Final exam

## Document Summary

Many experiments depend on several measured quantities, each of which has an associated error. The rules for combining the errors are given below. These would not be examined, but they can be used in your everyday work and will give you a feel for the magnitudes involved and more importantly will train you in the quantitative assessment of error. In all the following cases, the two independent measurements a and b with errors d a and. D b, are combined to give the quantity x which has the associated error d x. The straightforward combination of individual errors in sums or differences gives an overall error bound that is too pessimistic. It is unlikely that the individual errors will both be in the same direction, though not of course impossible. If x = a + b or x = a b , then: d x = {(d a)2 + (d b)2}