Abstract
Index of productive syntax (IPSyn; Scarborough, 1990) is a well-established measure of language acquisition (Washington et al., 2019 for English and Jamaican Creole; Nieminen, 2009 for Finish) that has not yet been adapted to many Slavic languages (except Russian; Chernobilsky, 2009). Our research question was: 1) What is the reliability and validity of the Czech adaptation of IPSyn and its subscales? Recordings of 110 children were made during free play at two time points: 2;6 years and then at 3;11.
On both occasions, their receptive vocabulary and grammar comprehension were assessed. We adapted the IPSyn measure to the needs of Czech.
The adaptation involves 54 items divided into four categories subscales as in the original English version: Nouns, Verbs, Questions/negation and Sentences. For transcript-based measures, in addition to IPSyn, we used mean length of utterance (MLU) and number of different words (NDW).
Czech adaptation of IPSyn was confirmed as a valid measure, as it was stable in time and showed concurrent and predictive relations with test- based measures. It also showed good internal consistency by Cronbach's alpha.