Reliability and concurrent validity of the information unit scoring metric for the story retelling procedure

This study reports the reliability and concurrent validity of the information units (IU) metric as an efficient method for quantifying the amount of information comprehended and reproduced on the Story Retelling Procedure (SRP) (Doyle et al., 2000). Subjects were 31 normal adults and 15 adults with aphasia. Significant and moderately high correlation coefficients were obtained for subjects with aphasia between %IUs and most linguistic measures including the correct information unit (Nicholas & Brookshire 1993, 1995) while low and non-significant correlations were found for many measures of language productivity, efficiency, and disruption. The %IUs among the four SRP forms within group was non-significant (p>.05) and correlations were significant and high. Normal speakers produced significantly greater %IUs than aphasic speakers. Standard error of measurement was low across forms for both groups (3-4%) and the range of individual subjects' performance overlapped between 20 and 27% for the group with aphasia and between 36 and 55% for the normal group. These results support the conclusion that %IU is a reliable and valid measure and differentiates aphasic from normal individuals better than normal individuals from persons with aphasia.