The late birthday effect in Western Australia

The Late Birthday Effect is a label given to the observation that students who fail to thrive in the early years of primary school are frequently those with late birthdays - e.g. in November and December. This effect is manifested in Western Australia where the rules for entering primary school result in late birthday students being developmentally less mature than the rest of their classmates. For how many years does this effect persist? Does it affect achievement in Senior Secondary School and, by implication, access to university? An analysis of tertiary entrance scores for 17 year old Western Australian school leavers in 1992 and 1993 showed that for students who enter school at the normal time and who progress at the normal rate there was no evidence of lower achievement by late birthday students; however, there was a conspicuous shortfall in the number of late birthday students in this year group. A comparison with birth statistics showed that late birthday students are more likely to be aged 18 on leaving senior secondary school. They are also less likely to be university-bound than students with early birthdays. A comparison of data from other Australian states confirmed the findings from Western Australia; namely, immature school starters are generally more likely to have their entry to school delayed or be made to repeat a year, but those who do progress at the the normal rate suffer no disadvantage in access to university. Since the rules for starting school differ from state to state, this effect is attributed to developmental maturity rather than seasonal factors affecting innate intelligence. Since the removal of students from the 'normal' cohort - by delaying school entry, making students repeat, or due to students leaving before the end of year 12 - does not increase the mean tertiary entrance score of late birthday students who progress at the normal rate, it is concluded that such interventions are unrelated to academic potential