以下是引用cjdong在2009-4-19 22:52:00的发言: michael哥们学过statistics吗? 你想想多少degree of freedom would yield a statistically significant result? 40 years of date = degree of freedom is 39。if you pass the t-test on a 39 d.f., of course you get statistically significant result.
right, but just means statistically significant. For the sample itself isn't large enough to provide a unbiased estimate. when i was studing econometrics, some emprical result provided by the textbook said, salary is significant higher for workers received higher education. That makes no sense as so many college graduates can't find a job with dismal salary. Ppl should be more cautious when making decisions, and even more cautious when he give advices, |