In an experiment, evaluate the validity of the steps leading up to the conclusion for it to be valid. Random and systematic errors can contribute to the uncertainty of a measurement.

Accurate results are free from systematic and random errors and accuracy also involves trueness and precision. Precision is defined as the closeness of agreement between individual values.

The stratified random sample is always at least as accurate on the average as the random sample and its relative efficiency is a monotone increasing function of the size of the sample. No general ...