Table 1.

Summary statistics for the CTT- and IRT-Scaled PF scores from the SF-36 Version 1.0 across Assessment Times and the CTT- and IRT-based Change Scores from Baseline to Time of Follow-up Assessment

		CTT-Based Scoring				IRT-Based Scoring*
Assessment Time	N	Mean	SD	Min	Max	Mean	SD	Min	Max
Initial Visit	996	35.32	24.83	0	100	35.79	24.13	−7.40	110.68
6-Weeks	996	53.81	26.28	0	100	53.90	25.37	−7.40	110.68
3 Months	996	61.33	27.14	0	100	61.10	27.06	−7.40	110.68
6 Months	996	63.86	27.89	0	100	63.93	28.34	−7.40	110.68
1 Year	996	66.37	28.17	0	100	66.44	29.56	−7.40	110.68
Total	4980	56.23	29.13	0	100	56.23	29.13	−7.40	110.68
PF Change Score DeltaPF
6-Weeks - Baseline	996	18.48	26.60	−55	95	18.1	26.0	−63.3	108.6
13-Weeks - Baseline	996	26.00	29.20	−60	100	25.3	28.6	−53.7	118.1
26-Weeks - Baseline	996	28.53	29.99	−90	100	28.1	29.9	−95.6	118.1
52-Weeks - Baseline	996	31.04	30.50	−90	100	30.6	30.9	−92.3	118.1

^*Note that the linear transformation of the IRT-based scores to have the same mean and standard deviation as the CTT-base scores resulting in IRT-based scores where extreme values that could be less than 0 or more than 100