Re: [R] Robust ANCOVA

[Martin Maechler]

> David Winsemius 
> on Sun, 27 Mar 2016 19:30:31 -0700 writes:

>> On Mar 27, 2016, at 9:52 AM, HAMID REZA ASHRAFI via
>> R-help  wrote:
>> 
>> HiI have a set of data with two independent variables, a
>> pretest (covariate) and posttest (dependent variable).Can
>> anyone help me run robust ANCOVA?If you wish I can send
>> you the data file.yours [[alternative HTML version
>> deleted]]

> https://cran.r-project.org/web/views/Robust.html

> help(pac=MASS, rlm)

> # A starting point perhaps:

> MASS::rlm( Post ~ pre +IV1 + IV2, data=yourdataframe)

> David Winsemius Alameda, CA, USA

Indeed.
Or use the more sophisticated (and somewhat more robust /
efficient) methods from package 'robustbase'

install.packages("robustbase")
require("robustbase")
fm <- lmrob(Post ~ pre +IV1 + IV2, setting = "KS2014",
data=yourdataframe)


where recent research lead to the recommendation of  setting="KS2014",
which indeed maybe relevant for "ANCOVA".

Martin Maechler, ETH Zurich
(and maintainer of 'robustbase', hence "biased" !)

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Re: [R] Robust ANCOVA

[David Winsemius]

> On Mar 27, 2016, at 9:52 AM, HAMID REZA ASHRAFI via R-help 
>  wrote:
> 
> HiI have a set of data with two independent variables, a pretest (covariate) 
> and posttest (dependent variable).Can anyone help me run robust ANCOVA?If you 
> wish I can send you the data file.yours
>   [[alternative HTML version deleted]]

https://cran.r-project.org/web/views/Robust.html

help(pac=MASS, rlm)

# A starting point perhaps:

MASS::rlm( Post ~ pre +IV1 + IV2, data=yourdataframe)


-- 


David Winsemius
Alameda, CA, USA

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Re: [R] Robust ANCOVA

[Jim Lemon]

Hi Hamid,
This looks a bit like a repeated measures analysis, but for a simple
introduction to ANCOVA using R see the latter part of the following:

http://www.stat.columbia.edu/~martin/W2024/R8.pdf

Jim

On Mon, Mar 28, 2016 at 3:52 AM, HAMID REZA ASHRAFI via R-help
 wrote:
> HiI have a set of data with two independent variables, a pretest (covariate) 
> and posttest (dependent variable).Can anyone help me run robust ANCOVA?If you 
> wish I can send you the data file.yours
> [[alternative HTML version deleted]]
>
> __
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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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[R] Robust ANCOVA

[HAMID REZA ASHRAFI via R-help]

HiI have a set of data with two independent variables, a pretest (covariate) 
and posttest (dependent variable).Can anyone help me run robust ANCOVA?If you 
wish I can send you the data file.yours
[[alternative HTML version deleted]]

__
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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.