Many statistical methods (estimators) are available for estimating the consensus value (or average effect) and heterogeneity variance in interlaboratory studies or meta-analyses. These estimators are all valid because they are developed from or supported by certain statistical principles. However, no estimator can be perfect and must have error or…

A common procedure when conducting physics experiments is to repeat a measurement several times to calculate the mean and standard deviation. That might be the only instruction we give to students as a means to minimize random errors. However, that technique does not guarantee that the answer will be correct. It might give the same wrong answer…

A study was conducted to identify local item dependence (LID) in the context-dependent item sets used in an examination prepared for use in an introductory university physics class and to assess the effects of LID on estimates of the reliability and standard error of measurement. Test scores were obtained for 487 students in the physics class. The…