The Causes of Poor Eyesight among Primary School Students--A Longitudinal Study

國小學童視力不良原因縱貫資料之探討

本研究旨在探討國小學童一至五年級視力不良原因之探討。其中主要探討的變項分別為性別、家長職業以及學生的學習成就對國小學童視力不良的影響，並利用SAS9.1 MIXED的分析程序進行分析此一縱貫性資料。研究發現較佳的混合分析模式為精簡隨機斜率的模式(AIC=404.6，BIC=355.9)。利用此一模式，獲致國小學童視力不良會隨著時間的增加而加深；女生與男生視力不良起始點不同，但斜率相同。\r另外，研究亦發現，國小學童之性別與學習成就的交互關係有所不同；家長的職業在模式中並未達到顯著性的差異，亦即家長職業的不同並不會造成學生視力不良。

This study examines the causes of poor eyesight among 1st to 5th grade primary school students. We consider whether gender， parental employment， and student achievement affect the severity of the poor eyesight. The SAS 9.1 PROC MIXED， a flexible program suitable for fitting individual growth models， was used. A number of statistical models were compared， and we concluded that the reduced model with random slope (assumed compound symmetry， different for each group covariance matrix) was the best fitting model (AIC=404.6， BIC=355.9). Using this selected model， we observed a statistically significant decreasing poor eyesight trends. Female students and male students had initially different levels of eyesight but the same rate of decrease over time. However， significant differences in eyesight trends were found between high and low achievement groups when considering gender as well (interaction effect). Finally， we observed no significant effect of parental employment on the response pattern to poor eyesight.