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Anne-Wil Kruijt mail at awkruijt.nl
Mon Oct 16 17:20:03 CEST 2017

Apologies, where I wrote ‘method = “MN”’, it should have been ‘measure = “MN”’.

On 16/10/2017, 17:18, "Anne-Wil Kruijt" <mail at awkruijt.nl> wrote:

    Dear all,
    Thank you, professor Viechtbauer, for referring me to this list. 
    Delving into metafor’s mechanics I noticed that when ‘method = “MN” ‘ is specified in escalc(), its calculation of sampling variance (vi) is “vi <- sdi^2/ni”. I wondered why there is no option to use the(/a?) unbiased estimator “vi <- sdi^2/ni-1”. I’m considered to bypass the escalc step and ‘manually’ compute vi as sdi^2/ni-1 – but I’m hesitant because it isn’t an option in escalc() (when method = “MN”, i.e. when obtaining the ‘raw mean difference’ for input as yi). Does anyone have any insights to share on why it is or is not a good idea to use the ‘unbiased estimator’ in the context of a REML MA on raw mean difference values? 
    All best,

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