Summary | Example Command | Notes |
Re-labeling variables |
rename q8 uid |
Changes the variable q8 to the name uid |
Deleting Variables |
drop q8 |
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View typing info |
describe uid |
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Specify missing values |
mvdecode *, mv(-1) |
Changes all values in all variable with -1 to "missing
value"
Only works with non-string type variables |
View frequency of data values |
codebook numrecalledtask |
only interesting with non-string variables |
Create a set of labels for a variable's values |
label define percent 0 "a" 1 "b" 2 "c" |
The value of 0 is now called "a" in all printouts and the set of labels is called "percent" |
Destroy a label set |
label drop percent |
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Apply labels to a variable's values |
label values percentagecovered percent |
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Remove labels from a variable's values |
label values |
Summary | Example Command | Notes |
Saving changes |
preserve |
Be sure to execute this before the end of a "do" file or changes will be lost. |
Changing values |
replace q8 = "3268" in 11 |
Changes the 11th item's value in variable q8 to the value 3268 |
Combining Datasets |
merge uid using "2nd.dta" "3rd.dta" |
One dataset (the master) must be loaded before
merging with other datasets. You need to sort the master data by the
merge variable (ie "uid") before executing the merge.
The merge variable needs to have the same type (ie, "int") in all datasets. Merging creates variables named _merge with this meaning: _merge==1 obs. from master data |
Sorting |
sort uid |
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Converting from a string |
destring q8, generate(uid) |
Defaults to int? Must all of the data already be numerical? |
Converting from a string, but replacing nonnumerical data as missing values |
destring q65, generate (foo) force |
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Summary | Example Command | Notes |
Query variable values |
list uid if _merge == 1 |
Conditional query example |
Count the number of observations satisfying a given condition |
count count if _merge1 > 1 |
count the number of observations
count the number of observations where _merge1 is greater than 1 |
Summary | Example Command | Notes |
Chi-squared test |
csgof q34, expperc(6.7 24.2 38.2 24.2 6.7) |
Second parameter is the expected frequency of observations, shown is the expected frequencies in the normal distribution |
Frequency counts | tabulate q34 | Provides frequency counts, percents, and cumulative percents |
Return values |
return list
ereturn list sreturn list nreturn list |
list all return values for the last calculation
e-class for estimation class
|
Retreive a return value | display r(chi2) | |
Correlate two variables | corr q72 q79 | |
Chi-square test for independence | tabulate q62 q67, chi2 | |
Regress between two variables | reg a b | |
Regress with a categorical variable, treating it as binary variable | xi: reg a i.b | |
Summary | Example Command | Notes |
repeating a command over several variables |
foreach x of varlist q18 q19 q20 q21 q22 q23 q24 q25 q26 q27 q28 q29 q31 q32 q33 q34 q35 q36 q41 q42 q43 q44 q45 q46 q47 q48 q49 q50 q51 q52 q113 q114 q115 q116 q117 q118 q119 q120 q121 q122 q123 q124 { csgof `x', expperc(6.7 24.2 38.2 24.2 6.7) } |
repeats the command 'csgof' for all variables q18, q19,...,q123, q124 |
Suppress the output of a calculation | quietly count if `x' = . | |
Display a string | display "\begin{tabular}" | |
Format a value | display %9.2f = 22/7 | Show pi with at most 9 leading integers and round to the nearest hundredth |
Summary | Example Command | Notes |
open a connection to download packages |
net from URL |
the site needs |
install a package from the current connection | net install tab_chi | |
list installed packages | ado | |