A lower value indicates smaller class sizes. Andover (thick blue line) has one of the lowest values over the past ten years. Trend analysis indicates no significant change in ratio over time (r2=.3871). Including data for the past ten years and ranking districts based on median student to teacher ratio (the intersection of the second quartile (green) and third quartile (purple); “whiskers” indicate top and lowest quartile data), the seven districts indicated (+) have significantly (p<= .05) higher ratios than Andover (none were significantly lower). In 2017, Andover and Winchester had the lowest student to teacher ratio (13.1) of any of the comparison districts (Andover was also lowest in 2016).