Which of the statements is true relative to systematic error? (Select all that apply.)

Question

a. If the amount of the systematic error is known, true scores can be retrieved.
b. Systematic error may be decreased by proper instrument calibration.
c. Systematic error results in values that vary in one direction from the true scores.
d. Systematic error results from researcher fatigue or inattention.
e. Systematic error changes the mean but not the relative magnitude of the variance.

Answer 1

ANS: A, B, C, E
Observed score = true score + systematic error. Measurement error that is not random is referred to as systematic error. For example, a scale that weighed subjects three pounds more than their true weights demonstrates systematic error. All of the body weights would be higher, and, as a result, the mean would be higher than it should be. Systematic error results in error in one direction. Consequently, the mean is either higher or lower, but the relative magnitude of the variance should remain the same. Systematic error occurs because something else is being measured in addition to the concept.