**Statistics
for the**

**Social
Sciences Handout**

Richard
Barton (rick)
richard.barton@dartmouth.edu

Statistical
Consultant 179C
Berry Library

Academic
Computing

http://www.dartmouth.edu/comp/soft-comp/software/statistics/stataintro.html

http://www.dartmouth.edu/comp/soft-comp/software/statistics/statafaq.html

Stata is free software for Dartmouth students; the current version
is 11.

Software that you need can be downloaded from http://www.dartmouth.edu/software Click on the link for Macintosh Software or
Windows Software. Academic Applications
include Stata and KeyAccess. General
Productivity Applications include Stuffit Expander.

Students who bought their computers through Dartmouth should
already have KeyAccess and Stuffit installed.

**1)** Authenticate to the
download site using your blitzmail name and password.

**2)** KeyAccess (KSClient)
allows you to run keyserved software.
You must be logged on to keyserver.dartmouth.edu to install and run Stata.

**3)** Stuffit (Aladdin)
Expander can be used to decompress (unzip) files.

**4)** Stata (Intercooled).

When you download Stata, you may also receive a file called README
or license.txt that contains information you may need the first time you run
Stata.

You should **not** register
your copy of Stata or allow automatic updates.

**Command** Where you issue Stata command
statements.

**Results** Shows the commands you've entered
and the output of those commands. Upon seeing –more- at the bottom of the
window, enter continues and q quits.

**Review** Shows the most recent commands
entered. Highlighting a command here enters it in the command window.

**Variables** Lists the variables in the current
data set. Highlighting a variable here enters it in the command window.

**Data editor Opens** the current
data set in spreadsheet editor. This window must be closed out to return you to
the command window.

**Graph** Where graphs are displayed.

A
log file can be opened from the File\Log menu. Open a log file (with a
.log extension) when you start a Stata session to keep a record of what you
type and Stata's output.

Rows
are cases, columns are variables.

*.dta* indicates a data file
already in Stata format

*.txt* or *.raw* indicates data in ASCII (text) formats

*.xls* indicates data in an
Excel file

**Clear** Clears data out of memory.

**Search** If you make a mistake with a Stata command,
it may return an error message along with a return code {for example, r(199)}. The **search**
command can be used to get a more detailed description of the return code.

**Generate ** Computes a new
variable from an expression.

Most
analysis commands can be followed by a comma and a list of options.

Stata
11 also allows you to do many analyses from the Statistics menu.

**Tabulate** Gets counts and percents of subgroups for 1
or 2 variables.

**Summarize **Calculates summary statistics such as means and
sd’s.

**Correlate** Displays the correlation matrix for a list
of variables.

**Regress ** Fits a linear regression model of a dependent
variable on a single predictor or set of predictors

Stata 11 allows you to build
graphs from the Graphics menu, but it is simpler to build them from the command
window.

Bar
chart |
graph
bar x y z, |

Histogram |
histogram
x, |

Scatterplot |
scatter
y x, |

**More on data files**

You
may already have a data set that you wish to bring into Stata. The file can be either:

a)
Spreadsheet format (such as Excel);

b)
Tab
(or comma) delimited text format, where variable values always come in the same
order in a line

and separated by the delimiter; or

c)
Fixed
column format, where values for the same variable are always in the same set of
columns for each

case (row).

You
may need a *codebook* that indicates
the format of the file, what columns hold what variables, how missing values
are defined, what value labels should be applied, etc.

**Use** Opens a data file that is already in Stata
format. The directory path must be specified and can be obtained

from the
File/Filename menu

**Insheet** Will read data from a file
that is already in a spreadsheet format

**Infile **Will read freefield data and tab- or comma-delimited
data from a text file

**Infix **Will read fixed field data from a text (ASCII) file.

insheet id sex using *'c:\my documents\clients\hsb.raw'
* (PC
file path)