Hi list, is there any direct way to obtain confidence intervals for the regression slope from lm, predict.lm or the like? (If not, is there any reason? This is also missing in some other statistics softwares, and I thought this would be quite a standard application.) I know that it's easy to implement but it's for explanation to people who faint if they have to do their own programming... Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
Regression slope confidence interval
6 messages · Christian Hennig, Chuck Cleland, Achim Zeileis +1 more
?confint
For example:
> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
> group <- gl(2,10,20, labels=c("Ctl","Trt"))
> weight <- c(ctl, trt)
> lm(weight ~ group)
Call:
lm(formula = weight ~ group)
Coefficients:
(Intercept) groupTrt
5.032 -0.371
> confint(lm(weight ~ group))
2.5 % 97.5 %
(Intercept) 4.569340 5.4946602
groupTrt -1.025300 0.2833003
Christian Hennig wrote:
Hi list, is there any direct way to obtain confidence intervals for the regression slope from lm, predict.lm or the like? (If not, is there any reason? This is also missing in some other statistics softwares, and I thought this would be quite a standard application.) I know that it's easy to implement but it's for explanation to people who faint if they have to do their own programming... Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Chuck Cleland, Ph.D. NDRI, Inc. 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 452-1424 (M, W, F) fax: (917) 438-0894
On Thu, 29 Sep 2005, Christian Hennig wrote:
Hi list, is there any direct way to obtain confidence intervals for the regression slope from lm, predict.lm or the like?
There is a confint method: e.g.,
R> fm <- lm(dist ~ speed, data = cars)
R> confint(fm, parm = "speed")
2.5 % 97.5 %
speed 3.096964 4.767853
hth,
Z
(If not, is there any reason? This is also missing in some other statistics softwares, and I thought this would be quite a standard application.) I know that it's easy to implement but it's for explanation to people who faint if they have to do their own programming... Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
?confint
Thank you to all of you. As far as I see this is not mentioned on the lm help page (though I presumably don't have the recent version), which I would suggest... Best, Christian
On Thu, 29 Sep 2005, Chuck Cleland wrote:
?confint For example:
> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
> group <- gl(2,10,20, labels=c("Ctl","Trt"))
> weight <- c(ctl, trt)
> lm(weight ~ group)
Call:
lm(formula = weight ~ group)
Coefficients:
(Intercept) groupTrt
5.032 -0.371
> confint(lm(weight ~ group))
2.5 % 97.5 % (Intercept) 4.569340 5.4946602 groupTrt -1.025300 0.2833003 Christian Hennig wrote:
Hi list, is there any direct way to obtain confidence intervals for the regression slope from lm, predict.lm or the like? (If not, is there any reason? This is also missing in some other statistics softwares, and I thought this would be quite a standard application.) I know that it's easy to implement but it's for explanation to people who faint if they have to do their own programming... Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
-- Chuck Cleland, Ph.D. NDRI, Inc. 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 452-1424 (M, W, F) fax: (917) 438-0894
*** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
Why not use vcov() and the normal approximation ?
> ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
> trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
> group <- gl(2,10,20, labels=c("Ctl","Trt"))
> weight <- c(ctl, trt)
> lm.D9 <- lm(weight ~ group)
>
> cbind(estimate = coef(lm.D9),
+ lower = coef(lm.D9) - 1.96 * diag(vcov(lm.D9)),
+ upper = coef(lm.D9) + 1.96 * diag(vcov(lm.D9)))
estimate lower upper
(Intercept) 5.032 4.9369482 5.1270518
groupTrt -0.371 -0.5611037 -0.1808963
To address your needs, it might also be possible to write a method for
the generic of intervals() in package nlme.
Best,
Renaud
Christian Hennig a ??crit :
Hi list, is there any direct way to obtain confidence intervals for the regression slope from lm, predict.lm or the like? (If not, is there any reason? This is also missing in some other statistics softwares, and I thought this would be quite a standard application.) I know that it's easy to implement but it's for explanation to people who faint if they have to do their own programming... Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Renaud Lancelot Directeur Adjoint charg?? des Affaires Scientifiques Deputy Director for Scientific Affairs D??partement EMVT du CIRAD, TA 30/B Campus International de Baillarguet 34398 Montpellier Cedex 5 - France Tel. +33 (0)4 67 59 37 17 Secr. +33 (0)4 67 59 39 04 Fax +33 (0)4 67 59 37 95
Sorry, I forgot confint and I made a mistake in my suggestion which
should be:
cbind(estimate = coef(lm.D9),
lower = coef(lm.D9) - 1.96 * sqrt(diag(vcov(lm.D9))),
upper = coef(lm.D9) + 1.96 * sqrt(diag(vcov(lm.D9))))
Best,
Renaud
Christian Hennig a ??crit :
Hi list, is there any direct way to obtain confidence intervals for the regression slope from lm, predict.lm or the like? (If not, is there any reason? This is also missing in some other statistics softwares, and I thought this would be quite a standard application.) I know that it's easy to implement but it's for explanation to people who faint if they have to do their own programming... Christian *** --- *** Christian Hennig University College London, Department of Statistical Science Gower St., London WC1E 6BT, phone +44 207 679 1698 chrish at stats.ucl.ac.uk, www.homepages.ucl.ac.uk/~ucakche
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Renaud Lancelot Directeur Adjoint charg?? des Affaires Scientifiques Deputy Director for Scientific Affairs D??partement EMVT du CIRAD, TA 30/B Campus International de Baillarguet 34398 Montpellier Cedex 5 - France Tel. +33 (0)4 67 59 37 17 Secr. +33 (0)4 67 59 39 04 Fax +33 (0)4 67 59 37 95