Psychometric Properties (Standardization, Validity, and Reliability) of British Picture Vocabulary Scale (BPVS_II)

The British Picture Vocabulary Scale (BPVS_II) is one of the most applicable and common scales for measuring children’s language abilities. This scale is useful for educational, clinical and research uses.In this research the Persian and localized version of this scale is developed and corresponding standardized, reliability and validity tests are done. 180 subjects were selected randomly from among 5, 7, 9 and 11 years old children. Wechsler intelligence scale was used for measuring concurrent validity of the Persian version of British Picture Vocabulary Scale. The results are indicative of proper reliability, concurrent validity and diagnostic validity of the Persian version of British Picture Vocabulary Scale. Standardization results showed that the score distribution of 100 is at percentile rank of 50%. Examination of concurrent validity using Wechsler’s intelligence scale indicated the correlation 0.48 between verbal intelligence and vocabulary score. Also, examination of diagnostic validity indicated a significant difference between vocabulary scores of 5, 7, 9 and 11 years old children. Cronbach alpha was used for testing reliability. Cronbach alpha coefficient for 168 items of the Persian Version of British Picture Vocabulary Scale was calculated as 0.84. Based on these findings we can conclude that this vocabulary scale has proper psychometric characteristics for being applied by Persian-speaking children and individuals. Moreover, the larger variance seen in distribution of scores in this research in comparison to standardized samples studied in other countries probably indicates more class differences in the society considered in this research.