Practice effect is the change in performance resulting from repeated testing. In other words if a test is given to the child too soon, then his/her performance may improve due to the practice effect (remembering the test items).
Why do we need to know about practice effect? Its important to know regarding practice effect because following retesting we need to know whether the child’s performance has actually improved or is the improvement a result of retesting provided too soon.
When can the same test be readministered to a child? Major testing companies such as Pearson and Pro-ed use a 2 week interval between readminstrations of developmental tests for the purposes of test-retest reliability. Why do they do that? Well if you wait too long they can’t tell “if differences in scores are due to the test being unreliable or due to developmental factors.”
So how long should we wait to readminister the same test to a child?
It seems that waiting more than two weeks (e.g., 3-4 weeks) following original test administration should eliminate the practice effect. For more information regarding the practice effect in speech language testing click here and in cognitive testing click here