Probably you got NAs in some bootstrap results, or you got a 0 variance,
or you hat 0 observations in a group you compared to another group?
Check the data and the separate results!
Uwe Ligges
On 25.04.2012 09:28, O wrote:> Hello,
>
> I am comparing two ROC curves with bootstraping. However, some runs return
> "p-value = NA," and I have no clue why.
>
> Is this anyhow related to like sample size or no sufficient numbers of
> bootstraping? I used the default value (i.e. boot.n=2000), and the number
> of observations are quite big since I am comparing maps (e.g., the largest
> has more than 9 million observations).
>
> It'd would be great if someone could explain why this is happening.
>
> With thanks,
> OK
>
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