Which of the statements is true, relative to error? (Select all ...

[Marty]

Which of the statements is true, relative to error? (Select all that apply.)
 
  a. True score plus error score equals observed score.
  b. Random error of measurement increases the mean.
  c. The mean of the true measurements is equal to the mean of the observed measurements when there is no systematic error.
  d. No measurement of anything is ever correct.
  e. Measurement error always exists, if a straightforward measurement like counting is made often enough and by enough people.

Question 2

Tests of stability reliability, such as test-retest, can reveal random measurement error. Why is systematic measurement error not revealed when stability reliability determinations are made?
 
  a. Actually, reliability testing does not reveal the type of error: differences on test-retest can indicate problems with both random and systematic measurement error.
  b. Tests of stability reliability are not powerful enough to pick up systematic measurement error because of its subtlety.
  c. If an instrument systematically measures all blood pressures 10 points high, it will do so both at baseline and on retesting.
  d. The direction of the systematic measurement error is reversed on retesting, so it is not visible in the statistical analysis.

[apple]

Answer to Question 1

ANS: A, C, E
Observed score = true score + random error. Random error does not influence the mean to be higher or lower but, rather, increases the amount of unexplained variance around the mean. Measurement error is the difference between what exists in reality and what is measured by an instrument.

Answer to Question 2

ANS: C
Stability reliability is concerned with the consistency of repeated measures of the same attribute with the use of the same scale or instrument over time. It is usually referred to as test-retest reliability. This measure of reliability is generally used with physical measures, technological measures, and paper-and-pencil scales. The technique requires an assumption that the factor to be measured remains the same at the two testing times and that any change in the value or score is a consequence of random error.

[Marty]

Correct answers!

[apple]

Great! Please up vote