Basic commands

Question 1

wildcards

Answer 1

• • random string

? - one character

Question 2

create a new variable

Answer 2

generate [new variable name] = function

Question 3

DELETE A VARIABLE

Answer 3

drop [variable name]

Question 4

CREATE A NORMALLY DISTRIBUTED VARIABLE

Answer 4

generate [new variable name] = rnormal()

Question 5

SHOW DATA

Answer 5

list [variable name]

Question 6

CONVERT STRING VARIABLE TO NUMERIC VARIABLE

Answer 6

destring [string variable name], replace|generate

Question 7

DECLARE DATA SET TO BE TIME SERIES

Answer 7

tsset [date variable]

Question 8

USE A SUBET OF THE DATA

Answer 8

regress … if [variable] [condition]

. indicates a missing observation and has a large value; hence, “if [variable] < .” omits missing variables
& indicates “and”
== indicates “equality”
| indicates “or”

Question 9

OLS REGRESSION

Answer 9

regress [dependent variable] [regressor 1] [regressor 2] … [regressor N]

Question 10

OLS REGRESSION WITH HETEROSKEDASTICITY CORRECTION

Answer 10

regress [dependent variable] [regressor 1] [regressor 2] … [regressor N], vce(hc3)

Question 11

PANEL REGRESSION (GLS when using random effects)

Answer 11

xtreg [dependent variable] [regressor 1] [regressor 2] … [regressor N], [option]

For [option], use RE for random effects, BE for time-specific fixed effects, and FE for cross-sectional fixed effects.

Question 12

Prediction

based on last run OLS

Answer 12

predict [new variable name]

Question 13

Forecast Standard Error

based on last run OLS

Answer 13

predict [new variable name], stdb

Question 14

Residuals

based on last run OLS

Answer 14

predict [new variable name], residuals

Question 15

Estimated covariance matrix:

based on last run OLS

Answer 15

estat vce

Question 16

Residual plus fixed effects (total residual)

based on last run Panel Data regression

Answer 16

predict [new variable name], ue

Question 17

Fixed effects (individual specific residual component)
(based on last run Panel Data regression)

Answer 17

predict [new variable name], u

Question 18

Non-specific residual:

based on last run Panel Data regression

Answer 18

predict [new variable name], e

Question 19

TEST FOR NORMALITY

Answer 19

sktest [variable name]

Note: The null hypothesis is normality.

Question 20

PORTMANTEAU (Q) TEST FOR SERIAL CORRELATION

Answer 20

wntestq [variable name], lags(#)

Question 21

CORRELOGRAM

Answer 21

corrgram [variable name]

Question 22

BREUSCH-PAGAN TEST FOR HETEROSKEDASTICITY

Answer 22

hettest

run this after running a regression

Question 23

TESTS FOR ENDOGENEITY

Answer 23

estat endogenous
(run this after running a regression)

Question 24

Transformation:

First difference in the variable

Answer 24

D.[variable name]

Question 25

Transformation: | Variable lagged on period

Answer 25

L.[variable name]

Question 26

GRAPHING

Answer 26

twoway (scatter [y1 variable] [y2 variable] ... [x variable]) plot [y variable] [x variable]

Question 27

Write all subsequent commands and output to a file

Answer 27

log using [filename]

Question 28

Write all subsequent commands and output to a text file

Answer 28

log using [filename], text

Question 29

Suspend logging

Answer 29

log off

Question 30

Resume loggin

Answer 30

log on

Question 31

Stop logging and closes the log file

Answer 31

log close

Question 32

RESTRICT OPERATION TO A SUBSET OF THE DATA

Answer 32

[command] in [starting observation]/[ending observation]

Question 33

GENERATE CORRELATION MATRIX

Answer 33

correlate [variable name, variable name, ...]

Question 34

Gives number of observations, mean, standard deviation, minimum value, and maximum value of all variables in a list

Answer 34

summary [variable name, variable name, ...]

Question 35

Give summary measures for all variables

Answer 35

summary

Question 36

Gives a large number of summary measures, including median, skewness, and kurtosis

Answer 36

summary [variable name], detail

Question 37

Gives the result of arithmetic operations on two or more variables, i.e. +, -, /, *, ^. Also used for logarithmic (log(argument)) and exponential (exp(argument)) operations.

Answer 37

display [arithmetic operation]

Question 38

Gives Pr(Z < z) for a standard normal variable Z.

Answer 38

display normal(z)

Question 39

Gives the value z for which Pr(Z < z) equals p, Z~N(0,1)

Answer 39

display invnormal(p)

Question 40

Gives Pr(T > t) for a t-distributed variable T with n degrees of freedom

Answer 40

display ttail(n,t)

Question 41

Gives the value t for which Pr(T>t) equals p, for a t-distributed variable T with n degrees of freedom

Answer 41

display invttail(n,p)

Question 42

Gives Pr(F>f) , for an F-distributed variable F with n1 and n2 degrees of freedom

Answer 42

display Ftail(n1,n2,f)

Question 43

Gives the value f for which Pr(F > f) equals p, for an F-distributed variable F with n1 and n2 degrees of freedom

Answer 43

display invFtail(n1,n2,p)

Question 44

Searches help and online databases for information on the command or statement

Answer 44

FINDIT [command]

Question 45

Provides help on a specific command

Answer 45

HELP [command]

Question 46

Searches help text for the specified terms

Answer 46

SEARCH [terms]