[R] Is this correct?

Daniel Malter daniel at umd.edu
Mon Nov 24 08:35:34 CET 2008

Bill is right. Generally, a more appropriate type of question to the list
would, for example, be: I want to run OLS. What is the function to do it in
R (although this is a particularly stupid example as it is on the first
pages of almost all manuals)? You would typically write to the R list if you
want to get a certain thing done and can't get it done (assuming that it is
not homework!). The main difference to your question being that you already
know what the "thing" is (which, in your case, is your modeling question).

Therefore your question is generally not one that anybody here should
answer. You as the researcher determine which relationships are of interest
and which make sense. You should consult the tutor/TA of your class if you
have any questions what the relationships of interest are. S/he is getting
paid to help you. Go there and say: Here are my ideas...what do you think?
Second, if you are required to do this in R, they should give you materials
to learn R from, respectively they should teach you R. Further, there are
numerous sources/manuals out there from which to learn the basics of R. And
they are free as R is. Just google them. 


cuncta stricte discussurus

-----Ursprüngliche Nachricht-----
Von: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Im
Auftrag von Rlover
Gesendet: Sunday, November 23, 2008 9:46 PM
An: r-help at r-project.org
Betreff: [R] Is this correct?

I have to answer the following question for a homework assignment.

A researcher was interested in whether people taking part in sports at
university made more money after graduating, taking into account the
students' GPA. They sampled 200 alumni from a large university. The
variables are: income (income 10 years after graduating), sports (1 if they
did sports, 0 if they did not), and GPA (the grade point average at
university). Discuss the relationship between taking part in sports, GPA,
and income for these data. 

The R code I used so far is

Does sports predict GPA? 

> lm1<-lm(GPA~sports)
> summary(lm1)

Does sports predict income? 
> lm2<-lm(income~sports)
> summary(lm2)

Does GPA predict income? 
> lm3<-lm(income~GPA)
> summary(lm3)

Does sports predict income after accounting for GPA? 
> lm4<-lm(income~GPA+sports)
> summary(lm4)

Can someone let me know is the above is correct? I am not sure if to keep
all four regressions or only 1 and 4. Also, I need to plot the data on a
graph or table. Can anyone suggest how to do this? Thank you in advance :)

View this message in context:
Sent from the R help mailing list archive at Nabble.com.

R-help at r-project.org mailing list
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

More information about the R-help mailing list