Test-Retest Reliability of the Test of Infant Motor PerformanceCampbell Suzann K. PhD PTPediatric Physical Therapy: Summer 1999 RESEARCH REPORT: PDF Only Abstract The purpose of this study was to 1) assess test-retest reliability of the Test of Infant Motor Performance (TIMP) over a three-day period and 2) compare the effect on test-retest reliability of the TIMP of using same or different raters on the two test occasions. One hundred sixteen pairs of tests were performed on 106 infants (white, black, and Latino). Subjects, ranging in age from 32 weeks postconceptional age to 16 weeks past term, were categorized by medical risk for developmental disability (high, medium, or low). Ten raters (physical therapists and occupational therapists with documented rater reliability) participated in the study. Multiple regression analysis was used to assess the relationship between pairs of test scores and to evaluate the effect of same vs different raters on the similarity between scores on the two days. Test scores on the two days were correlated at 0.89 (p < 0.0001). Most of the variance in the score on the second occasion was explained by the score on the first, and there was no significant difference between pairs of scores based on rater. Fifty-four percent of the scores differed by fewer than eight points of a possible 170 points. These findings support the conclusion that the TIMP has sufficient test-retest reliability for use in clinical practice to assess infant motor performance across the age range for which the test was designed. © 1999 Lippincott Williams & Wilkins, Inc.