Table 3.

Requirements for a Standardized Aphasia Test

	Requirement	Related psychometric indices
1.	Standardized administration and scoring	Inter-examiner reliability Test-retest reliability
2.	Items covering intended domains of language functioning	Face validity Content validity Item discriminability Construct validity
3.	Discrimination between relevant characteristics of impairment	Content validity Construct validity
4.	Items of varying difficulty	Item difficulty index
5.	Sufficient number of items for stability of measurements	Internal consistency Test-retest reliability Item reliability Construct validity
6.	Minimal effect of demographic (age, education) and other cognitive variables (attention, memory, intelligence) on performance	Lack of correlation between these demographic/cognitive factors and test performance Representative normative sample
7.	Differentiation between individuals with aphasia, individuals without cognitive or language impairments, and individuals without aphasia but with other cognitive deficits due to brain damage	Criterion validity Sensitivity Specificity Construct validity
8.	Measurement of similarity to results on known aphasia tests	Concurrent validity