请教各位一个research的基本问题导师给了我一个T or F 的问题
when P is 0.001, meaning there is 1% probability that the null hypothesis is not being true.
我的理解
If P=0.01, so there is a 1% chance that the data groups have no difference while 99% of the chance that the groups have differences. So this is statistically significant as p is less than 0.05.
P value is the probability of getting the results if the null hypothesis is true. So we have a 1% of getting the result if the null hypothesis is true which is no difference.
所以我的答案是 false
然后prof说不对啊，这是基本问题咋答不上来呢。正确答案是true
我之后请教队友，队友跟我理解的还是一样。。
请教了工作友人医生们，还是跟我去理解的一样啊。
难道做了一堆trials发布过N篇papers的也理解错了这个P and Ho吗？
导师还没来得及回答我问题，已经email她。今天我不死心七早八早又找了一堆basic的书，almond ans walker 就说
“the smaller the p value the smaller the likelihood that the null hypothesis is true”...
这也是跟我理解的一样啊。
是在无解，请教各位大神来看看。
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你和你的导师都错的
先来说导师,他错在这个statement的表述上。 他对p value的理解犯了大多数人都会犯的错误。
a P value is the probability of obtaining an effect at least as extreme as the one in your sample data, assuming the truth of the null hypothesis. 如果你不能obtain a more extreme value,你就不能推翻null hypothesis.而这个p value和how true the null hypothesis是没有关系的，它只是一个likelihood.不能等同为1.23%(假设p=0.0123)的几率null hypothesis is true.
再来谈一下你的回答, 首先你没有弄清楚是哪个p value， 0.01是实际算出来的p value,还是alpha？如果你给出的就是导师的问题的全部，那0.01就是alpha了。导师想要考你对alpha的理解，alpha is now 0.01=1%。而你以为0.01是实际p value 小于0.05，基于这个你说导师的错误的。所以你的回答导师自然说你是错的。另外你对p value的理解也和导师一样，犯了同样的错误。
最后说一下正确的表述： if p value is 0.01 (confidence level 99% or alpha=0.01), 0.01 is the smallest level of significance at which the null hypothesis would be rejected.
我们只会说没有足够的证据to reject null hypothesis or prove there is an effect or difference.而不会说我们就92%的把握。。。。。end of the day, we are dealing with samples to obtain the interpretation on the population.
a P value is the probability of obtaining an effect at least as extreme as the one in your sample data, assuming the truth of the null hypothesis. 如果你不能obtain a more extreme value,你就不能推翻null hypothesis.而这个p value和how true the null hypothesis是没有关系的，它只是一个likelihood.不能等同为1.23%(假设p=0.0123)的几率null hypothesis is true.
再来谈一下你的回答, 首先你没有弄清楚是哪个p value， 0.01是实际算出来的p value,还是alpha？如果你给出的就是导师的问题的全部，那0.01就是alpha了。导师想要考你对alpha的理解，alpha is now 0.01=1%。而你以为0.01是实际p value 小于0.05，基于这个你说导师的错误的。所以你的回答导师自然说你是错的。另外你对p value的理解也和导师一样，犯了同样的错误。
最后说一下正确的表述： if p value is 0.01 (confidence level 99% or alpha=0.01), 0.01 is the smallest level of significance at which the null hypothesis would be rejected.
我们只会说没有足够的证据to reject null hypothesis or prove there is an effect or difference.而不会说我们就92%的把握。。。。。end of the day, we are dealing with samples to obtain the interpretation on the population.
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