Northland College R FAQ

The following are links to answers for frequently asked questions by Northland College students while using R to perform statistical analyses. Other questions may be answered by reading the class text or e-mailing Derek Ogle.

Running R

• How do I obtain R for my home computer?
• How do I install the NCStats package?
• When I load the NCStats package R says that it cannot find some other packages.
• R cannot find the NCStats package.
• I am using a Mac and having problems with TCL/TK
• Why is the R prompt a "+" rather than a ">"?
• I can't remember the names of objects that I have created.
• R says that "a previously saved workspace has been restored".
• I accidentally saved the workspace image. How do I remove it?
• R can't find the function I want to use.

• How do I obtain TINN-R for my home computer?
• How do I configure TINN-R to match the Northland College computers?
• How do I change R to SDI mode to work properly with TINN-R?
• Is there a similar editor for the Macintosh?

Reading Data Files

• Where are the data files that Prof. Ogle provides for us?
• Is there an easy way to enter data into R?
• How do I change the working directory?
• When I change the working directory I cannot see my data file?
• read.table() does not find my data file.
• When I view my text file in Notepad it looks like data is missing.
• read.table() says that "line X did not have Y elements"
• read.table() says there are "more columns than column names"
• My data file was read but my variables are messed up.
• My variables are called V1, V2, ...

Using Data Frames and Subsetting

• How do I select two groups of a factor variable?
• I've subsetted my data by a factor but groups that I don't want still appear.

Specific Functions

• My frequency table contains unwanted levels.
• My bar chart contains unwanted levels.
• What does the chisq.test() warning mean?
• R says the alternative hypothesis is true, even though the p-value > a.
• The df for my two-sample t-test contains decimals.
• Dunnett's test in glht() does not use the level for the "control" group that I want it to use.
• How do I simulate data for a one-way ANOVA using mrnorm()?
• How do I simulate data for a two-way ANOVA using mrnorm()?

Formatting Written Documents (and some MS Word hints)

• How should I label and refer to tables and figures?
• How do I make R output look nice without having to physically type in spaces or tabs?
• How do I make the my document single-spaced?
• How do I make a, m, or s or other Greek Letters?

Older FAQs

• R can't find droplevel().
• R can't find Levenes().
• R can't find Summary().
• When I attach a data frame R says that some variables are "masked."
• How do I detach an attached data frame?
• How do I see which data frames are attached?
• Is it possible to detach all data frames at once?