Edmund M. Kosmahl, PT, EdD




a. Validity is a measurement concept that asks whether a measurement system actually measures what it's supposed to (i.e., joint range of motion in the case of goniometry)

b. Goniometric measurements can be invalid; usually because of poor stabilization. (see positioning and stabilization)

RELIABILITY a. Reliability is a measurement concept that asks whether successive measurements are consistent, repeatable or reproducible. Upper extremity measurements are more reliable than lower extremity measurements. 1) intratester reliability (same tester on different occasions)- measurement error should be less than 5 degrees

2) intertester reliability (different testers) - measurement error probably greater than 5 degrees

b. to maximize reliability always use the same:
1) goniometer
2) positioning
3) procedure
4) examiner

copyright 1999 E. Kosmahl