可以忽视boxplot和histogram（都显示data是rightskewed,所以a,b中选：））samplesize：7776~Basedupontheboxplotandhistogramofthe(untransformed)countdata,whichoneofthefollowingstatementsiscorrect:Selectone:a.Thediagr

Question

可以忽视boxplot 和 histogram（都显示data是right skewed,所以a,b中选：））sample size：7776~
Based upon the boxplot and histogram of the (untransformed) count data,which one of the following statements is correct:
Select one:
a.The diagrams indicate that the data is skewed to the right,but (given the sample size) it is not possible to conclude that the data from which the sample was taken is not normally distributed
b.The diagrams indicate that the data is skewed to the right,and (given the sample size) we may conclude that the data from which the sample was taken is not normally distributed
c.The diagrams indicate that the data is normally distributed,and (given the sample size) we may conclude that the data from which the sample was taken is normally distributed
d.The diagrams indicate that the data is normally distributed,but (given the sample size) we may not conclude that the data from which the sample was taken is normally distributed
e.None of the other answers to this question is true.

Answer 1

要得到正态分布,样本数据本身不需要是正态分布,可以是偏态分布（即左右不对称）,如这题的图形.根据中心极限定理(central limit theorem),偏态分布有个特点,当样本增大时,其均数趋向正态分布.这题样本7776足够大,所以基本上必然是趋向正态分布的.所以选a