arcsine transformation with negative values

[Christoph Scherber <Christoph.Scherber@uni-jena.de>]

Dear S list members,

I am currently analyzing a dataset that consists of differences of percentage
values - i.e., the values may range from -100% to +100%.

How can I transform these data in order to meet the assumptions of parametric
statistics? I´ve been thinking of adding a constant and then using a
transformation like

transformed<-asin(sqrt(p))

But the p values would then not lie in the interval [0..1].

I would be most grateful for any advice.

Best regards
Christoph.



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