Hi Scott,

Thanks for this, as expected family is significant when i perform a ANOVA - one question, how do i assess model fit if

> The R2 increasing could be just due to the fact that you are adding more information
 
Thanks,

Chris
On 29 Mar 2011, at 12:40, Scott Chamberlain wrote:

You could try anova(explanation_mod_FD) which will give you the test for the family variable instead of breaking it down into each level of the variable. The R2 increasing could be just due to the fact that you are adding more information even if it doesn't turn out to be significant. 

Scott
On Monday, March 28, 2011 at 10:19 AM, Chris Mcowen wrote:

> Dear list,
> 
> I am modelling the distribution of a variable FD, FD is the functional diversity contained within ecoregions i have various predictors temperature, rain fall, population density etc etc, I have ( through AIC and stepwise) arrived at the most likely model the predicts the distribution of FD. However when i look at the community composition of the ecoregions that deviate from the model they have community compositions that are heavily skewed to certain families.
> 
> So i would like to know the effect on the family composition on FD in relation to the other factors so i can say something like: anthropogenic and environmental factors explained 10 percent of the observed variance in FD however the composition of the community explained.. %
> 
> I have done 
> 
> explanation_mod_FD <- lm(Residuals_FD~Temperature+Agriculture+Population) which had a r sqaured of 0.10 and all correlates were significant
> 
> now i tried 
> 
> explanation_mod_FD <- lm(Residuals_FD~Temperature+Agriculture+Population + FAMILY, correlation = exponential)
> 
> However, as expected i guess, i get
> 
> (Intercept) 4.944e-04 5.219e-03 0.095 0.9245 
> Temperature 2.311e-04 1.716e-05 13.470 < 2e-16 ***
> Agriculture -2.637e-09 3.567e-10 --7.393 1.84e-13 ***
> Population 3.389e-06 6.380e-07 5.311 1.16e-07 ***
> FAMILYAlliaceae -1.598e-03 5.432e-03 -0.294 0.7686 
> FAMILYAlstroemeriaceae -6.986e-03 5.419e-03 -1.289 0.1974 
> FFAMILYAmaryllidaceae -3.045e-03 5.344e-03 -0.570 0.5689 
> etc etc
> 
> Where each family is broken down.
> 
> Multiple R-squared: 0.13
> 
> Does this suggest that adding FAMILY explains 3% more of the variance than not adding it? 
> 
> What i want to know is A) is the compostion of family within the region significant and by how much.
> 
> Any ideas or suggestion would be gratefully received, thanks in advance.
> 
> Chris
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