R help - Nov 2009 - A comparison between span in lowess method and h in sm.regression

Dear All,

I have fitted a bivariate and an additive model on a monthly temperature from
1987-2007 via nonparametric regression and would like to compare?between these
models via F-test, but having difficulty in determining the possible values of
span?with lowess method.

For instance, these two models are defined in R as: 

######################################################
bivariate.model <- sm.regression(c(month,year), Temperature, h = c(0.2,0.8))?
additive.model <- gam(Temperature~lo(month, span=A) + lo(year,span=B)) 
######################################################

However, i notice the sm.regression function uses h as a?smoothing parameter
?whilst the gam function uses span as a smoothing parameter, and these models
can't just simply be compared?straight? forward,?but?few?adjustments should
be made on the values of span in gam function,?corresponding to the values of h
in sm.regression function.

Could anyone please advice me ?the possible values of A and B in the gam
function above? I'd would be very grateful for any idea and suggestion
towards this issue.

Thank you
Fir