Cleber Nogueira Borges wrote:
my linear model is y=c+a*x1+b*x2 i tried to found a, c, b by the
use of:
mymodel<-lm(y~1+x1+x2) where y, x1, x2 are 3 vectors with the same
length
the result is a=NA.so i want to know where is the problem.
It's the sum of x1 and x2 equal to one?
run the command: round( sum( c(x1,x2) ),12)==1
may I ask how this may solve the problem?
You concatenate the two vectors x1, x2; calculate the sum of it;
round it to 12 digits; and then check whether it is equal to 1.
Roland
ok, sorry for incomplete question...
this problem smell like mixture modelling... (chemical mixture for
example)
this command not solve the problem, but check one condition...
It still doesn't do what you think... all.equal(x1+x2,1) is more like it.
A more general approach is summary(lm(x1~x2)) or just plot (x1~x2) to
check for a perfect linear relation, or possibly a constant x1.
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