factor variables in logistic regression
On 05/11/2016 08:00 AM, ch.elahe via R-help wrote:
Hi all, I have a plot for TSTMean vs. SNRMean and both of these variables are factors. How can I use Logistic Regression for factor variables? Currently I use model=lm(TSTMean~SNRMean,data=df) but when I check summary(model) I get this error: r error in quartile.default (resid) factors are not allowed thanks for any help, Elahe
First of all, lm() is for linear regression, not logistic regression. For logistic regression you need to use glm() and make sure you set the correct family (see ?glm). I don't recall if glm() accepts a factor outcome but if not, you would need to re-code it to 0/1. Kevin
Kevin E. Thorpe Head of Biostatistics, Applied Health Research Centre (AHRC) Li Ka Shing Knowledge Institute of St. Michael's Hospital Assistant Professor, Dalla Lana School of Public Health University of Toronto email: kevin.thorpe at utoronto.ca Tel: 416.864.5776 Fax: 416.864.3016