Re: [R] Multiple regression in R

2014-05-30 Thread Rui Barradas
Hello, lm() is designed to work with data.frames, not with matrices. You can change your code to something like dat <- data.frame(price, pred1 = c(5,6,3,4,5), pred2 = c(2,1,8,5,6)) fit <- lm(price ~ pred1 + pred2, data = dat) and then use the fitted model to do predictions. You don't have to

Re: [R] Multiple regression in R

2014-05-29 Thread Sarah Goslee
Hi, I'd do it like this, making use of data frames and the data argument to lm. traindata <- data.frame(price=price, predictor1=predictor1, predictor2=predictor2) testdata <- data.frame(predictor1=3, predictor2=5) predict(lm(price ~ ., data=traindata), testdata) Note that you don't have to speci

Re: [R] Multiple regression in R

2014-05-29 Thread Safiye Celik
Solved! Here is the solution in case it helps others: The easiest way to get past the issue of matching up variable names from a matrix of covariates to newdata data.frame column names is to put your input data into a data.frame as well. Try this price = c(10,18,18,11,17) predictors = cbind(c(5,6

[R] Multiple regression in R

2014-05-29 Thread Safiye Celik
I want to perform a multiple regression in R and make predictions based on the trained model. Below is an example code I am using: price = c(10,18,18,11,17) predictors = cbind(c(5,6,3,4,5),c(2,1,8,5,6)) predict(lm(price ~ predictors), data.frame(predictors=matrix(c(3,5),nrow=1))) So, based on th

Re: [R] Multiple regression in R - unstandardised coefficients a

2011-08-23 Thread JC Matthews
Thankyou for your replies, you've answered my question and given me more to think on. I guess it is unwise to draw any conclusions from the standardised results for these reasons. James. --On 22 August 2011 17:30 +0100 ted.hard...@wlandres.net wrote: On 22-Aug-11 15:37:40, JC Matthews wrote

Re: [R] Multiple regression in R - unstandardised coefficients a

2011-08-23 Thread Ista Zahn
On Tue, Aug 23, 2011 at 7:54 AM, JC Matthews wrote: > Thankyou for your replies, you've answered my question and given me more to > think on.  I guess it is unwise to draw any conclusions from the > standardised results for these reasons. No, by all means try to draw conclusions! Isn't that the p

Re: [R] Multiple regression in R - unstandardised coefficients a

2011-08-22 Thread Ted Harding
On 22-Aug-11 15:37:40, JC Matthews wrote: > Hello, > > I have a statistical problem that I am using R for, but I am > not making sense of the results. I am trying to use multiple > regression to explore which variables (weather conditions) > have the greater effect on a local atmospheric variable.

Re: [R] Multiple regression in R - unstandardised coefficients are a different sign to standardised coefficients, is this correct?

2011-08-22 Thread Ista Zahn
Hi JC, You have interactions in your model, which means that your models specifies that the coefficients for hum, wind, and rain should vary depending on the value of the other two (and depending on their own value actually, since you also have quadratic effects for each of these variables in your

[R] Multiple regression in R - unstandardised coefficients are a different sign to standardised coefficients, is this correct?

2011-08-22 Thread JC Matthews
Hello, I have a statistical problem that I am using R for, but I am not making sense of the results. I am trying to use multiple regression to explore which variables (weather conditions) have the greater effect on a local atmospheric variable. The data is taken from a database that has 20391