Table 3

Heterogeneity and inconsistency in the diabetes example
Q statistic Number of studies Degrees of freedom p value
Qnet 96.98 26 27-9=18 <0.001
Qinc 22.53 26 16-9=7 0.002
Qhet 74.45 26 27-16=11 <0.001
<a onClick="popup('http://www.biomedcentral.com/1471-2288/13/35/mathml/M118','MathML',630,470);return false;" target="_blank" href="http://www.biomedcentral.com/1471-2288/13/35/mathml/M118">View MathML</a> 4.38 2 2-1=1 0.036
<a onClick="popup('http://www.biomedcentral.com/1471-2288/13/35/mathml/M119','MathML',630,470);return false;" target="_blank" href="http://www.biomedcentral.com/1471-2288/13/35/mathml/M119">View MathML</a> 42.16 3 3-1=2 <0.001
<a onClick="popup('http://www.biomedcentral.com/1471-2288/13/35/mathml/M120','MathML',630,470);return false;" target="_blank" href="http://www.biomedcentral.com/1471-2288/13/35/mathml/M120">View MathML</a> 6.45 3 3-1=2 0.040
<a onClick="popup('http://www.biomedcentral.com/1471-2288/13/35/mathml/M121','MathML',630,470);return false;" target="_blank" href="http://www.biomedcentral.com/1471-2288/13/35/mathml/M121">View MathML</a> 21.27 6 6-1=5 0.001
<a onClick="popup('http://www.biomedcentral.com/1471-2288/13/35/mathml/M122','MathML',630,470);return false;" target="_blank" href="http://www.biomedcentral.com/1471-2288/13/35/mathml/M122">View MathML</a> 0.19 2 2-1=1 0.665

The decomposition of the Q statistics as well as the degrees of freedom of the corresponding chi-squared distributions and the p values are shown. In addition the considered number of studies are displayed. Only one study is observed for the following designs: plac:acar, plac:piog, plac:sita, plac:vild, acar:SUal, metf:piog, metf:SUal, piog:rosi, rosi:SUal, plac:acar:metf. For this reason, the corresponding <a onClick="popup('http://www.biomedcentral.com/1471-2288/13/35/mathml/M117','MathML',630,470);return false;" target="_blank" href="http://www.biomedcentral.com/1471-2288/13/35/mathml/M117">View MathML</a> statistics are not shown.

Krahn et al.

Krahn et al. BMC Medical Research Methodology 2013 13:35   doi:10.1186/1471-2288-13-35

Open Data