what is the difference between using function predict() and coef() in prediction
On Dec 10, 2011, at 11:48 AM, tony333 wrote:
X8 = c(0.42808332, 0.14058333, 0.30558333, 0.09558333, 0.01808333, -0.09191666, -0.11441666, -0.12941666, 0.13808333, -0.31691666, 0.25308333 ,-0.20941666 ,0.02808333, -0.04441667, -0.43691666) xy.lm = lm(Y~X8) z = predict(xy.lm,list(X8=X8)) sz = coef(xy.lm)[1]+(coef(xy.lm)[2])*X8 is the same result in this step but when use the prediction as T8=c(-0.05691667, -0.09441666 , 0.31308333 ,-0.59941665 ,-0.33941666 ,-0.64441665,-0.55691665 ,-0.01191667 ,0.22558333, -0.30691666 , 0.97808331 , 0.49808332,-0.30941666 ,0.41808332 , 0.42308332) zz = predict(xy.lm,list(T8=T8))
The first "T8" should be..^^ .... "X8" > zz = predict(xy.lm,data.frame(X8=T8)) > ss = coef(xy.lm)[1]+(coef(xy.lm)[2])*T8 > identical(unname(zz), ss) [1] TRUE
ss = coef(xy.lm)[1]+(coef(xy.lm)[2])*T8 here gives me different value and zz = z = sz i do not know the reason for that what i understand about predict() act exactly like using coef() but now do not know the difference
If you give predict alist or data.fram whose name is different than that of the origianl variable ist will be ignored.
thank you for respond -- View this message in context: http://r.789695.n4.nabble.com/what-is-the-difference-between-using-function-predict-and-coef-in-prediction-tp4173961p4180577.html Sent from the R help mailing list archive at Nabble.com.
______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD West Hartford, CT