[R] p-value from GEE why factor 2*pnorm?
Benilton Carvalho
bcarvalh at jhsph.edu
Mon Jun 11 17:46:59 CEST 2007
Well, AFAIK, the definition of a p-value is the probability of
observing something at least as extreme as the observed data.
If you observed z, and Z follows a std-normal
p-value = P( Z < -abs(z) ) + P( Z > abs(z) )
= 2*P ( Z > abs(z) )
= 2*pnorm(z, lower.tail=FALSE)
try z=0 (you should get 1) and z=1.96 (you should get 5%)
b
On Jun 11, 2007, at 11:34 AM, Carmen Meier wrote:
> Benilton Carvalho schrieb:
>> the recommendation was to use lower.tail=FALSE.
>>
>> b
>>
>> O
> but then the results are significant and this does not match the
> observation.
> The results are matching the observations if the formula is
>
> pnorm(c
> (1.8691945,0.5882351,2.4903091,1.9287802,2.3172983,2.2092593,2.2625959
> ,1.6395695),
> lower.tail =TRUE)
>
> so I have any unknown problem .... anywhere :-(
>
> REgards Carmen
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