[R] sphericity calculation

[Uwe Ligges]

Darren Weber wrote:

> Dear Prof. Baron,
> 
> thankyou for your pdf paper on using R, at
> 
> http://www.psych.upenn.edu/~baron/rpsych.pdf
> 
> I am currently interested in the sphericity notes on pp. 45-47.
> 
> The equation on p. 46 suggests the following R calculation:
> 
> D <- k^2 * ( mean(diag(S)) - mean(S) )^2
> 
> while the notes in the pdf indicate the following:
> 
> D <- k^2 * ( mean(S) - mean(diag(S)) )^2
> 
> Can you please consider this and advise the correct calculation?


Both are equal! Mathematical calculations you should really know from 
school show that
(a - b)^2 = (b - a)^2
.....

Uwe Ligges



> Best, Darren
> 
> 	[[alternative HTML version deleted]]
> 
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