search for: dataslice

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2010 Apr 27
3
Problem calculating multiple regressions on a data frame.
...me error message) I have also tried to follow the approach suggested by Charles Sharpsteen (http://www.mail-archive.com/r-help@r-project.org/msg74759.html) with similar results. The code is as follows: theModels <- by( theTestLineal, list( theTestLineal$ids, zongTestLineal$variable), function( dataSlice ){ linMod <- lm( value ~ seqMonth, data = dataSlice ) # Slope and intercept may be recovered from the output of the coef() function: intercept <- coef( linMod )[1] slope <- coef( linMod )[2] # The R-Squared value is returned by the summary() function: rsq <- summary( linMod )[[ '&...
2009 Nov 05
2
Using a by() function to process several regression (lm()) functions
Hello, Thank you very much for looking at this. I have a "seasonal" user for R. I teach my undergrads and graduates students statistics using R and often find myself trying to solve problems to process student collected data in an efficient way. In this case, I have a data.frame with multiple observations. These are gas concentrations in a chamber and are used to measure into rates,