i do not know what is the difference between predict() and coef()
i use the two function give me different result zz = predict(xy.lm,list(T8=T8)) ss = coef(xy.lm)[1]+(coef(xy.lm)[2])*T8 where is t8 is the data used in prediction did not use in the fitting in training sample where every sample is 15 value |
Hi
Did you find any difference? The results shall be same (with only rounding error). Can you show us some example where you get substantial difference? Regards Petr > > i do not know what is the difference between predict() and coef() > i use the two function give me different result > zz = predict(xy.lm,list(T8=T8)) > ss = coef(xy.lm)[1]+(coef(xy.lm)[2])*T8 > where is t8 is the data used in prediction did not use in the fitting in > training sample where every sample is 15 value > > > -- > View this message in context: http://r.789695.n4.nabble.com/what-is-the- > difference-between-using-function-predict-and-coef-in-prediction- > tp4173961p4173961.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > [hidden email] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ [hidden email] 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. |
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)) 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 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. ______________________________________________ [hidden email] 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. |
In reply to this post by PIKAL Petr
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)
Y =c(370.63333 , 887.63333 ,3610.88333 , 435.13333 , 1261.38333 , -741.11667,-3231.36667 ,-708.36667 ,-646.36667, -3652.86667 ,-2196.11667 ,-5552.61667,-92.11667, -1635.86667 ,-3264.61667) 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)) 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 thank you for respond |
In reply to this post by tony333
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. > > ______________________________________________ > [hidden email] 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 ______________________________________________ [hidden email] 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. |
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