R help - Nov 2006 - Compare linear regressios for significant differences of the slopes

Hi

I have (8 measures * 96 groups) = 768 datasets for which I did linear
regressions using lm().

Now I want to compare the slopes for each of the 8 measures in each of 
the 96 groups. As I understand , I can not use
> anova(lm1, ..., lm8)
as the lm1 ... lm8 are based on different datasets.

I also read in previous discussions in this list, that I can see if the 
slope +- stddev(slope) overlap, but this seems a long process for the 
huge number of comparisons.

Therefore my question: is there a way to compare the slopes of lm() 
which are based on different datasets and what is the easiest way to do
it for this large number of datasets?

Thanks in advance for your help,

Rainer

-- 
Rainer M. Krug, Dipl. Phys. (Germany), MSc Conservation
Biology (UCT)

Department of Conservation Ecology and Entomology
University of Stellenbosch
Matieland 7602
South Africa

Tel:		+27 - (0)72 808 2975 (w)
Fax:		+27 - (0)21 808 3304
Cell:		+27 - (0)83 9479 042

email:	RKrug at sun.ac.za
       	Rainer at krugs.de

Hi

I haven't received any ideas yet - I just wanted to confirm if this is a 
simple question? Should I follow the idea of checking if slope +- stddev 
slope overlap?

Thanks,

Rainer

Rainer M Krug wrote:
> Hi
> 
> I have (8 measures * 96 groups) = 768 datasets for which I did linear
> regressions using lm().
> 
> Now I want to compare the slopes for each of the 8 measures in each of 
> the 96 groups. As I understand , I can not use
>> anova(lm1, ..., lm8)
> as the lm1 ... lm8 are based on different datasets.
> 
> I also read in previous discussions in this list, that I can see if the 
> slope +- stddev(slope) overlap, but this seems a long process for the 
> huge number of comparisons.
> 
> Therefore my question: is there a way to compare the slopes of lm() 
> which are based on different datasets and what is the easiest way to do
> it for this large number of datasets?
> 
> Thanks in advance for your help,
> 
> Rainer
> 

-- 
Rainer M. Krug, Dipl. Phys. (Germany), MSc Conservation
Biology (UCT)

Department of Conservation Ecology and Entomology
University of Stellenbosch
Matieland 7602
South Africa

Tel:		+27 - (0)72 808 2975 (w)
Fax:		+27 - (0)21 808 3304
Cell:		+27 - (0)83 9479 042

email:	RKrug at sun.ac.za
       	Rainer at krugs.de