Figure CNF4.2 shows the average numeracy scores of this group and of year four students in Tonga in previous PILNA cycles. The score in 2021 was slightly lower than in PILNA 2018 (493.49), but about the same as in PILNA 2015 (487.33), while the standard deviation for this group was greater than all previous PILNA cycles. In 2018 (SD=50.24) and 2015 (SD=47.74). This means that the distribution of overall numeracy scores in 2021 was more spread out than in previous PILNA cycles. More analysis needs to be done to understand whether these differences in scores are statistically significant.

Standard deviation shows how close data points are to the average. A lower standard deviation means that data points are, overall, closer to the average; a higher standard deviation means that data points are, overall, further away from the average.