standard deviation above the average score”explain what“1 standard deviation above the average score"means。能用英语回答就更好了，

统计学里，计算z-score，就是标准计分的公式为(x-population mean)/standard deviation
就是 （计算的样本对象 减去 总体期望） 再除以 总体标准差。
公式表示样本在总体中的位置。
z-score=0表示恰好处于总体正态分布的*位置，数值恰好等于数学期望。
z-score=1就表示你问的“1 standard deviation above the average score”了.....相当于“计算对象比数学期望高出一个标准差”的意思。
其实你把算z-score的公式中standard deviation乘到z-score一边，就能看出来了是不、

"1 standard deviation above the average score" means that the observation value minus the population mean just equals to 1 standard deviation.The average score is the population mean.
Assume a observation selected from a population follows normal distribution (u,s^2) is x,we can calculate its Z-score = (x-u)/s = n,and we say that the observation value is n standard deviation above (positive n) or below (negative n) the average score.