Objectives(2) To examine the utility of CHat, M-CHAT and CHAT-3 Consistency and accuracy between the three screening tools To test the applicability of Symbolic Play Test in the Chinese population in determining the mental maturity of children To explore the possibility of CHat-3 for population-wide or targeted high risk group screeningObjectives (2) • To examine the utility of CHAT, M-CHAT and CHAT-3 • Consistency and accuracy between the three screening tools • To test the applicability of Symbolic Play Test in the Chinese population in determining the mental maturity of children • To explore the possibility of CHAT-3 for population-wide or targeted high risk group screening