{smcl}
{* April 15, 2008 @ 21:14:12}{...}
{cmd:help metandi postestimation} {right: (Roger Harbord)}
{right:also see: {help metandi}}
{hline}
{title:Title}
{hi:metandi postestimation} {hline 2} postestimation tools for metandi
{title: Description}
{p 4 4 2}
Many of Stata's standard postestimation tools
will not work after {helpb metandi},
or won't work as expected,
as {helpb metandi} reshapes the data before fitting the model.
{p 4 4 2}
The notable exception is {cmd:predict},
which can be used to obtain posterior predictions (empirical Bayes estimates)
of the sensitivity and specificity in each study ({cmd:mu}),
as well as various statistics that may be useful for
detecting outliers (e.g. {cmd:ustd})
and influential observations ({cmd:cooksd}).
{p 4 4 2}
{helpb metandiplot} graphs the results from {cmd:metandi}.
{title:Syntax for predict}
{p 8 17 2}
{cmd:predict} [{help datatypes:type}] {it:newvarlist}
[{it:{help if}}] [{it:{help in}}]
[{cmd:,} {it:statistic}]
{p 4 4 2}
where {it:statistic} is
{p 8 25 2}{cmd:mu}{space 11}posterior predicted (empirical Bayes)
sensitivity and specificity; the default{p_end}
{p 8 25 2}{cmd:u}{space 12}posterior means
(empirical Bayes predictions, BLUPs)
of random effects{p_end}
{p 8 25 2}{cmd:sdu}{space 10}posterior standard deviations
of the random effects{p_end}
{p 8 25 2}{cmd:ustd}{space 9}standardized posterior means of random effects
{p_end}
{p 8 25 2}{cmdab:li:npred}{space 6}linear predictor
with empirical Bayes predictions plugged in. linpred = xb + u{p_end}
{p 8 25 2}{cmdab:co:oksd}{space 7}Cook's distance for each study.
Only available when model was fitted using {cmd:gllamm}.{p_end}
{p 4 4 2}
Most of the above statistics require two new variables to store them,
one for the statistic associated with sensitivity, and
one for the statistic associated with specificity.
If {it:newvarlist} contains only one {it:newvar},
the statistics associated with sensitivity and specificity
will be stored in {it:newvar}{hi:1} and {it:newvar}{hi:0} respectively.
{cmd:cooksd}, however,
is computed once for each study
and therefore requires only one {it:newvar}.
{title:Remarks}
{p 4 4 2}
If the model was fitted using {cmd:gllamm},
the predictions are obtained using {helpb gllapred},
whose help page contains further details of the statistics available.
See also the GLLAMM manual
({help metandi##gllammmanual:Rabe-Hesketh, Skrondal & Pickles 2004})
and {help metandi##rhs:Rabe-Hesketh & Skrondal (2005)}.
If the model was fitted using {cmd:xtmelogit},
the predictions are obtained using {cmd:predict} -
see {help xtmelogit postestimation##predict}.
{title:Examples}
{p 8 14 2}{cmd:. metandi tp fp fn tn}
{p 4 4 2}
Add empirical Bayes estimates to {helpb metandiplot}:
{p 8 14 2}{cmd:. predict eb}
{p 8 14 2}{cmd:. metandiplot, addplot(scatter eb1 eb0)}
{p 4 4 2}
Check for particularly influential observations using Cook's distance:
{p 8 14 2}{cmd:. predict cook, cooksd}
{p 8 14 2}{cmd:. scatter cook studyid, mlabel(author)}
{p 4 4 2}
Check for outliers using standardized predicted random effects
(interpretable as standardized level-2 residuals):
{p 8 14 2}{cmd:. predict ustd_Se ustd_Sp, ustd}
{p 8 14 2}{cmd:. scatter ustd_Se ustd_Sp, xscale(rev) mlab(studyid) xline(0) yline(0) }
{title:Also see}
{p 4 13 2}
Online: {helpb gllapred}, {helpb metandi}, {helpb metandiplot}