The schools score 1 point for every year it graduates any student who scored above 275 for PSLE. The school also gets an additional 0.1 points for every student that it sends to the list of top 10 national graduates of PSLE. Schools are further ranked according to the recency of its good performance in PSLE. The Index is a weighted total of the annual scores, and more recent results are given higher weightage.
We do NOT profess our method to be either definitive or accurate in assessing the relative academic strengths of Primary schools in Singapore. The best measure should be the total number of passes, weighted with the total number of quality passes across all schools. In the absence of such data, however, we feel what we have is the best anyone can publicly offer at the moment.
Note that any school with a Index of less than 1 could well be an anomaly, especially if the score was attained several years ago. On the other hand, schools that consistently managed to churn out students scoring >275 in the last 3 years consecutively probably have a good functioning teaching programme in place. Not all schools are ranked in this table. Any school that is not in the list are those that have not produced a student scoring >275 in the last 10 years.