[R] p-value from GEE why factor 2*pnorm?

[Benilton Carvalho]

the recommendation was to use lower.tail=FALSE.

b

On Jun 11, 2007, at 11:21 AM, Carmen Meier wrote:

> I got an answer for the other question (thank you)
>
> But there is another question  (I am afraid this is a basic  
> question ...)
>
> In this tread there is a hint hwo to calculate the p-vlue of an GEE:
>> _http://finzi.psych.upenn.edu/R/Rhelp02a/archive/74150.html_
>>
>> Then, get the P values using a normal approximation for the
>> distribution of z:
>>
>> /> 2 * pnorm(abs(coef(summary(fm1))[,5]), lower.tail = FALSE) /
>> (Intercept) TPTLD  0.00000000 0.04190831
>
> 1. why is the result multiplicated  with 2? There is a P-value  
> between 1 and 2
> with the results below and multiplicated with 2:
>
> 2*pnorm(c 
> (1.8691945,0.5882351,2.4903091,1.9287802,2.3172983,2.2092593,2.2625959 
> ,1.6395695),
> lower.tail =TRUE)
>
> Regards Carmen