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st: metan command STATA IC 12.1
From
shadi Kalantarian <[email protected]>
To
statalist <[email protected]>
Subject
st: metan command STATA IC 12.1
Date
Wed, 10 Jul 2013 15:54:46 -0400
I am doing a meta-analysis in which I will need to generate pooled
prevalence rates. For each study, prevalence and its 95% confidence
interval was calculated using exact binomial (cii command, exact level
(95)). I used metan command in two different ways:
1) metan p se, random
2) metan p U95 L95, random
When I use the first command (the one with standard error) the
reported confidence intervals in the forest plot are completely
different from those calculated with cii command. Why does this
happen? and does this mean I should not use metan p se command?
study total cases SE (standard error) p (prevalence) L95 U95
one 51 9 0.053382 0.176471 0.084009 0.308726
two 45 11 0.064064 0.244444 0.128823 0.395371
three 30 4 0.062063 0.133333 0.037554 0.307219
four 12 3 0.125 0.25 0.054861 0.571858
. metan p l95 u95 , random
Study | ES [95% Conf. Interval] % Weight
---------------------+---------------------------------------------------
1 | 0.176 0.084 0.309 38.55
2 | 0.244 0.129 0.395 27.40
3 | 0.133 0.038 0.307 26.77
4 | 0.250 0.055 0.572 7.28
---------------------+---------------------------------------------------
D+L pooled ES | 0.189 0.119 0.259 100.00
---------------------+---------------------------------------------------
Heterogeneity chi-squared = 1.58 (d.f. = 3) p = 0.664
I-squared (variation in ES attributable to heterogeneity) = 0.0%
Estimate of between-study variance Tau-squared = 0.0000
Test of ES=0 : z= 5.31 p = 0.000
. metan p se , random
Study | ES [95% Conf. Interval] % Weight
---------------------+---------------------------------------------------
1 | 0.176 0.072 0.281 38.22
2 | 0.244 0.119 0.370 26.54
3 | 0.133 0.012 0.255 28.27
4 | 0.250 0.005 0.495 6.97
---------------------+---------------------------------------------------
D+L pooled ES | 0.187 0.123 0.252 100.00
---------------------+---------------------------------------------------
Heterogeneity chi-squared = 1.84 (d.f. = 3) p = 0.605
I-squared (variation in ES attributable to heterogeneity) = 0.0%
Estimate of between-study variance Tau-squared = 0.0000
Test of ES=0 : z= 5.68 p = 0.000
Thank you,
Shadi Kalantarian MD MPH
Research Fellow
Massachusetts General Hospital
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