Figure CWF4.2 shows the average writing scores for this group and for year four students in Tonga in previous PILNA cycles. The average writing score for these students in 2021 (488.97) was higher than in 2015 (454.31) but lower than in 2018 (501.20). The standard deviation for the average year four reading scores in 2021 (37.76) was, however, lower than in 2015 (93.35) and 2018 (63.44). This shows that the spread of writing scores in 2021 was narrower than in previous PILNA cycles.

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.