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. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: Optom Vis Sci. 2010 Aug;87(8):543–548. doi: 10.1097/OPX.0b013e3181e61bd8

Table 2.

Summary statistics from Rasch analysis using WINSTEPS for different instruments or subscales are shown. Mean item measure is set to zero for all instruments. Mean person measures near zero indicate good targeting of an instrument. Person and item separation reliability values greater than 0.8 are acceptable.16 The model expectation for item infit mean square is one.

Instrument (or subscale) Mean Rasch Person Measure (SE) Mean Rasch Item Measure (SE) Person Separation Reliability Item Separation Realiability Item Infit Mean Squares
24-item +0.13 (0.09) 0.00 (0.12) 0.87 0.91 1.04
Seven-item −0.06 (0.23) 0.00 (0.33) 0.80 0.93 0.99
Near Subscale −0.54 (0.22) 0.00 (0.59) 0.57 0.93 0.99
Near Subscale w/ appendix −0.55 (0.17) 0.00 (0.34) 0.72 0.94 0.99
Distance Subscale −0.17 (0.22) 0.00 (0.31) 0.51 0.80 0.99