# Doing linear prediction with R: How to access the predicted parameter(s)?

I am new to R and I am trying to do linear prediction. Here is some simple data:

test.frame<-data.frame(year=8:11, value= c(12050,15292,23907,33991))

Say if I want to predict the value for year=12. This is what I am doing (experimenting with different commands):

lma=lm(test.frame$value~test.frame$year) # let's get a linear fit summary(lma) # let's see some parameters attributes(lma) # let's see what parameters we can call lma$coefficients # I get the intercept and gradient predict(lm(test.frame$value~test.frame$year)) newyear <- 12 # new value for year predict.lm(lma, newyear) # predicted value for the new year

Some queries:

if I issue the command lma$coefficients for instance, a vector of two values is returned to me. How to pick only the intercept value?

I get lots of output with predict.lm(lma, newyear) but cannot understand where the predicted value is. Can someone please clarify?

Thanks a lot...

## Answers

intercept:

lma$coefficients[1]

Predict, try this:

test.frame <- data.frame(year=12, value=0) predict.lm(lma, test.frame)