##### Code for Multivariable Modeling and swamping


### Import the data


datum=read.csv(file.choose())
head(datum)


### Plot the data


plot(Size~Sex,data=datum) # plot relationship between size and sex
plot(Size~Age,data=datum) # plot relationship between size and age


### single variate analyses between size and age


results=lm(Size~Age,data=datum) ### single variable analysis of age
summary(results)
#note that estimated effect of age is pretty good estimate
#Residual standard is a little large, however.


### single variable analysis between size and sex


results2=lm(Size~Sex,data=datum) ### single variable analysis of sex
summary(results2)
#note that estimated effect of sex is o.k. (large SE), but not significant
#too much noise
#residual standard error is very large


### multi-variable analysis


results3=lm(Size~Age+Sex,data=datum) ### Note that plus doesn't actually mean 'add' - it means include both in model
summary(results3)
# Note that estimated effect of age and sex are right on