STATA 11 for Windows SAMPLE SESSION - Food Security Group ...

Stata 11 Sample Session Section 2 – Restructuring Data Files – Table Lookup & Aggregation
Computing quartiles
The xtile command using if
The new variable does not yet have a variable label. To
assign a variable label:
1. Click on Data, then Data utilities, then Label
utilities, then Label variable.
2. In the Variables: box, select cprod_ae
3. In the Attach label to variable (up to 80
characters) box, type
Calories produced per adult equivalent per day
4. Click on the copy button, switch to the do-file
editor, paste the command, switch back to the
dialog box and click on Ok.
5. Add a comment to explain what you have done.
The Stata commands are:
generate double cprod_ae= cprod_tt/ae/365
label variable cprod_ae "Calories produced per adult
equivalent per day"
Before we can produce the table we want, we have to
create one more variable, denoting which calorieproduction
quartile each household falls into within each
district. The Stata command to use is called xtile. This
command is not available through the menus. To look at
the structure of the command, we can use the Help menu.
1. Click on Help / Stata command.
2. In the Command: box, type xtile and click on Ok.
Under the Description heading, the definition of xtile is
that it is a command that categorizes a variable into the
specified quantiles and places the information into a new
variable. Examples can be found under the Examples:
heading. Since we want to divide the data into quartiles
within each district, we can use the “if” subcommand,
e.g.,
xtile quart = cprod_ae if district == 1, nq(4)
where
quart is the new variable that is created
cprod_ae is the variable used to rank the data
district is the controlling variable
nq(4) is short for nquantiles(number) which
specifies the number of quantiles to use.
1. Click on Statistics then Summaries, tables and
tests then Summary and Descriptive Statistics
then Create variable of quantiles
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