Question

10. (8 pts.) (a) Choose any of the analyses in questions 7, 8, or 9. Use it to explain or define the concept of "sources of error variance”. (b) Next, identify a specific source of error variance in the dataset you chose. Explain or show how the source you identify meets your definition of "error variance". (c) Why do researchers want to minimize error variance?

Answer 1

(a) Sources of Error Variance:

-test construction (variation may consist within items on a test or between tests)
-test administration (sources of error may stem from the testing environment -also test-taker variables (emotional problems, discomfort, lack of sleep, drugs/medication) -examiner-related variables such as physical appearance and demeanour may play a role)
-test scoring and interpretation (-computer testing reduces error in test scoring -many tests still require expert interpretation (ex: projective tests) -subjectivity in scoring can enter into behavioral assessment)

(b) No data file is attached for this part

(c) Error variance does not invalidate an experiment. The more error variance, the more difficult it is to detect the effects of the independent variable. We have the means to calculate error variance.

-Sources of error variance are

difference among participants

Random variations in the experimental setting and procedure

Other unsystematic influences