Rating Scale Instrument Quality Criteria

Rating Scale Instrument Quality Criteria
Criterion	Poor	Fair	Good	Very Good	Excellent
Targeting	> 2 errors	1-2 errors	< 1 error	< .5 error	< .25 error
Item Model Fit Mean-Square Range Extremes	< .33 - >3.0	.34 - 2.9	.5 - 2.0	.71 - 1.4	.77 - 1.3
Person and Item Measurement Reliability	<.67	.67-.80	.81-.90	.91-.94	>.94
Person and Item Strata Separated	2 or less	2-3	3-4	4-5	>5
Ceiling effect: % maximum extreme scores	>5%	2-5%	1-2%	.5-1%	<.5%
Floor effect: % minimum extreme scores	>5%	2-5%	1-2%	.5-1%	<.5%
Variance in data explained by measures	<50%	50-60%	60-70%	70-80%	>80%
Unexplained variance in contrasts 1-5 of PCA of residuals	>15%	10-15%	5-10%	3-5%	<3%
This Table has been developed by William P. Fisher, Jr. based on the Rasch literature and his many years of experience conducting Rasch analyses in different settings.

Rating Scale Instrument Quality Criteria. Fisher, W.P. Jr. … Rasch Measurement Transactions, 2007, 21:1 p. 1095