Message-ID: <B713F62B-D799-4EB3-BB7C-4CDD8BE20D2F@gmail.com>
Date: 2011-10-14T09:32:33Z
From: Peter Dalgaard
Subject: Wilcoxon and the use of simulation
In-Reply-To: <1318577972292-3904036.post@n4.nabble.com>
On Oct 14, 2011, at 09:39 , shl2a wrote:
> Dear forum users,
>
> It's 3:35am and I am swamped with statistics homework lol
> I'm terrible with R and this time I have no idea what the prof wants. Here
> is the question:
>
> Consider the (two-??sample) Wilcoxon rank statistic T = ?rank(Xi). For
> n1=106 and n2=192, determine by simulation the ?=.05 critical point for
> testing H0: ?=0, H1:?<0.
> We can do this as follows:
>
> For m=10000 (no wimpy m=200 or 500 as in the book),
> draw m=10000 subsets of size 106 from the integers 1:298
> using repeatedly the command
>
> xdat = sample(1:298, size=106).
>
> For each such subset, the value of the Wilcoxon is sum(xdat). Be sure to
> answer the following question: why is it unnecessary to calculate ranks?
>
> Any help would be greatly appreciately at this time.
Well, he wants you to use your brain, not ours... This is not a list for helping people with their homework. Look through your teaching materials and notes and see if your friendly prof hasn't already provided an example of doing replicated simulations, drawing a histogram of the results, etc.
--
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com