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  • Not sure what statistical test to use; McNemar versus Kappa

    I am discussing with some friends a paper which is very interesting for me due that I am doing a similar study. They have used McNemar to get the p-values in Table 6 [ McNemar exact test (2-sided statistical testing] for each scallop separately (Crosstables). and 95% confidence intervals were calculated with Tango's statistics. However I do not think is appropriate, I think that K concordance test would be more appropriate, and I am not sure that Tango is also the most appropriate any suggestions?? I attach the paper
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  • #2
    Ana Maria,

    It looks like they did both McNemar/Tango and kappa statistics, see the second half of the "Statistical Analysis" portion of the Methods Section. Table 6 only has the McNemar/Tango p-values but the kappa statistics are embedded in the text.

    Although both methods are used, they are used in different situations. The McNemar/Tango is used to show that the 3D method is better (more accurate) than the 2D method. The kappa statistic would not be useful for this situation since it measures agreement, and if there was disagreement it wouldn't tell you whether the disagreement was in the right direction or not, or whether it was significant. The kappa is used to compare both 2D and 3D methods with surgical findings (the gold standard). In this case you want there to be agreement and the kappa can tell you the extent to which the two agree. The downside of kappa even in this situation is that there are no tests or rules for determining a "good" kappa. They use one of the common rules-of-thumb.

    Regards,
    Joe

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    • #3
      Joe Do you know how can I get Kappa to compare 2D & 3D findings with surgical findings??

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      • #4
        with Stata of course..

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        • #5
          Hello, Ana,

          I good start, if you didn't try it before, is just typing - help kappa - in the Stata command window.

          Best,

          Marcos
          Best regards,

          Marcos

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