too much data heterogeneity

1. difficulty level of getting into top 5 vs. the rest of top20-30 is very different. but the data of addimision to top 5 is thin even for those top high schools. so depending on your target, need to separat the datapoints for different purpose

2. addmission to top 5 is too thin, some legacy addimission will make it hard to draw meaningful conclusion. 

agreed with others:

 关键是看你自己孩子的性格和实力，承压能力强不强。你说的这些学校对你孩子的升学概率没什么大的差异