I'm trying to add a fitted quadratic curve to a plot.
abline(lm(data~factor+I(factor^2)))
The regression which is displayed is linear and not quadratic and I get this message:
Message d'avis : In abline(lm(data ~ factor + I(factor^2)), col = palette[iteration]) : utilisation des deux premiers des 3 coefficients de régression
which means:
Use of the first 2 of the 3 regression coefficients
When running only the lm() function I don't get any messages.
Here is a sample data:
factor <- 1:7
data <- c(0.1375000,0.2500000,0.3416667,0.4583333,0.7250000,0.9166667,1.0000000)
Answer
Instead of using abline, use fitted, which gives you a vector the same length as your input of the predictions:
fitted(lm(data~factor+I(factor^2)))
# 1 2 3 4 5 6 7
# 0.1248016 0.2395833 0.3699405 0.5158730 0.6773810 0.8544643 1.0471230
Thus, something like:
plot(factor, fitted(lm(data~factor+I(factor^2))), type="l")