本帖最後由 lo_pak 於 2011-7-16 12:02 編輯
回復 51# zoids
I don't want to explain the maths here, it seems like you are lacking the background for stats (quite time consuming for me , those stuffs should be the next chapter after normal distribution, standard deviation?? Seems like you only know mean, mode and median... ). Whatsoever, there's whole bunch of info on web you can search for random sampling, population size, sample size... they are all simple concepts in stats...
BTW, it's not easy to setup an unbiased and objective survey (esp. for those setup by HKU, they are famous), if you really want to know more you have to study a little harder NOW...
知之為知之, 不知為不知, 是為知也... |