I may be missing something here, but evidently the two P-values can
differ. If you want one, don't ask for the other!
Nick
[email protected]
Janet Hill
Thank you for that I agree with the 0.05 but
unfortunately I did not write the protocol.
The object was to list all the variables that had
p<0.05 which worked for ache (0.047) but not for diet
(0.114). I realise that I am doing something stupid in
the syntax but I can't see it. I thought that I could
"automate" the process rather than typing in 50
ologits and examining the results.
--- Nick Cox <[email protected]> wrote:
> I don't follow this. Your results for diet show a
> P-value of 0.0407
> which Stata is evidently happy to consider as <
> 0.05.
>
> A quite separate point is that to many conservative
> statisticians your
> P-values no longer have the orthodox interpretation
> after this shotgun
> screening process.
>
> Nick
> [email protected]
>
> Janet Hill
>
> I have to run typically 50 variables separately in
> ologit as part of a screening process and some of
> the
> models fail with no convergence. I have tried the
> following to trap the error and continue the
> analysis:
>
> set more off
> foreach x of var chew speech appear1 ......{
> capture quietly ologit `x' wmean if surface==1
> if _rc==0 & chi2tail(e(df_m),e(chi2)) < 0.05 di
> "`x'"
> }
> set more on
>
> Hoping just to print out those variables with a
> model
> probability < 0.05.
>
> This typically produces several variables:
> ache
> diet
> glass
> etc.
> When I subsequently analyse these variables the
> model
> associated with ache has p<0.05, but diet does not
>
> .. ologit ache wm if surface==1,nolog
>
> Ordered logistic regression
> Number of obs = 15
> LR
> chi2(1) = 4.83
>
> Prob
> > chi2 = 0.0280
> Log likelihood = -16.888841
> Pseudo R2 = 0.1251
>
>
------------------------------------------------------------------------
> ------
> ache | Coef. Std. Err. z
> P>|z|
> [95% Conf. Interval]
>
-------------+----------------------------------------------------------
> ------
> wmean | 1.23758 .6219381 1.99
> 0.047
> .0186035 2.456556
> .. ologit ache wm if surface==1,nolog
>
>
> .. ologit diet wm if surface==1,nolog
>
> Ordered logistic regression
> Number of obs = 15
> LR
> chi2(1) = 4.19
>
> Prob
> > chi2 = 0.0407
> Log likelihood = -3.7955935
> Pseudo R2 = 0.3556
>
>
------------------------------------------------------------------------
> ------
> diet | Coef. Std. Err. z
> P>|z|
> [95% Conf. Interval]
>
-------------+----------------------------------------------------------
> ------
> wmean | -1.967477 1.24521 -1.58
> 0.114
> -4.408044 .4730897
>
> I would be grateful if somebody could point out my
> programming error.
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
