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Re: ANOVA with mean and SD?


From: Michael Grossbach
Subject: Re: ANOVA with mean and SD?
Date: Wed, 03 Sep 2008 17:18:35 +0200
User-agent: Thunderbird 2.0.0.16 (Windows/20080708)

The balanced ANOVA requires equal numbers of parameters. If you'd place
your three treatment groups' data in one vector Y though, using a second
dummy vector of length(Y) to denote which group a data point belongs to
then ANOVA can deal with unequal numbers of data points (untested):
dummy = [ones(length(y(:,1)), 1); ...
 ones(length(y(:,2)), 1)*2; ...
 ones(length(y(:,3)), 1)*3];
Y = [y(:,1); y(:,2); y(:,3)];
[pval, f, df_b, df_w] = anova (Y, dummy);

If your data are not normally distributed use kruskal_wallis_test (for
one-factorial designs).

Michael

Wolfgang Schechinger wrote:
Dear experts, I need to analyze 2500 parameters in 3 groups by ANOVA, means I want todetect which parameters vary between the groups. For every group I have a table with
number of data points (may vary from group to group)
mean
standard deviation.
(3x3 columns, 2500 rows)

As I understand the anova(y,g) function, one needs to supply the raw data and 
there should be the same number of data points per colum at least for each 
parameter.

Is there a way to adapt the function to my data set, or is there another 
function one could use?

What can I do when my data does not follow a normal distribution?

Many thanks for your help!

Wolfgang




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