Re: st: RE: Question regarding meta-analysis for proportions.

[Austin Nichols <austinnichols@gmail.com>]

Nora Trabulsi <nora.trabulsi@mail.mcgill.ca> :
If you are working on a log odds scale as you should for meta-analysis
of proportions, you will have problems with the point estimate, not
just the standard error.  One way forward would be to use the mean and
variance of the posterior distribution in a Bayesian framework, with a
uniform prior in each study.  Probably true Bayesians would object to
this miscegenation of Bayesian and frequentist approaches, but I am
betting that if you simulate the approach, it dominates others in
terms of MSE.  It does not seem justifiable to remove the 2 studies
with the highest outcome from the analysis since you will introduce
bias by selecting on the outcome.

On Thu, Jul 28, 2011 at 3:48 PM, Nora Trabulsi
<nora.trabulsi@mail.mcgill.ca> wrote:
> Thanks for your response
>
> Yes, this is with using binomial exact. When I generated the proportions and their standard errors, the results shown in the the stata window shows "binomial exact".
> Here is the output:
>
>                                                        -- Binomial Exact --
>        Variable                Obs             Mean    Std.    Err.            [95% Conf. Interval]
>
>                                5               1                       0               .4781762           1*
>
> (*)     one-sided,      97.5%   confidence      interval
>
>                                                        -- Binomial Exact --
>        Variable                Obs             Mean    Std.    Err.            [95% Conf. Interval]
>
>                                4               1                       0               .3976354           1*
>
>
>
> So what do you think?
>
> Nora
>
>
>
>
>
> On 2011-07-28, at 3:38 PM, Forshee, Richard wrote:
>
>> Have you considered using exact binomial confidence intervals instead of the approximation to the Normal distribution?
>>
>>
>> Richard A. Forshee
>>
>> -----Original Message-----
>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nora Trabulsi
>> Sent: Thursday, July 28, 2011 2:36 PM
>> To: statalist@hsphsun2.harvard.edu
>> Subject: st: Question regarding meta-analysis for proportions.
>>
>> Hi
>>
>> I am doing a meta analysis on proportions of patients responding to specific treatment. I generated p(proportions) and  se(standard errors). Then , I used the metan command:
>>
>> metan p se, random
>>
>> The problem that I have encountered is that two of the studies that are included in the analysis had a response rate of 100%, however, they were small in size, 4 and 5 patients only. So this generated a problem as they had standard errors = zero and they were excluded form the analysis and forest plot.
>>
>> I tried to use the inverse weight command before running metan:
>>
>> gen cons=1
>> vwls p cons, sd(se)
>>
>> but it would still address the same problem, that std error theta cannot be negative or zero.
>>
>> Any idea how to solve this problem, or is it justifiable to remove those 2 studies from the analysis?
>>
>> Thanks
>>
>> Nora Trabulsi

*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/