Reliability and Validity of Goniometric iPhone Applications

The purpose of this study is to determine the test-retest and inter-rater reliability and concurrent validity of two iPhone goniometric applications in the measurement of active shoulder external rotation as compared to a standard manual goniometer. The scientific hypotheses for this study are as follows: 1. There will be significant Pearson correlations (\>.8) to demonstrate test-retest reliability for each of the tools between the 1st and 2nd round of testing as assessed by novice testers. 2. There will be significant intra-class correlation coefficients (\>.8) to demonstrate inter-rater reliability between the novice tester and the experienced tester for each of the three tools. 3. There will be significant Pearson correlations (\>.8) to demonstrate concurrent validity between the standard goniometer and the photo capture application, the standard goniometer and the accelerometer-based application and the photo capture application with the accelerometer-based app. as assessed by novice testers.