Introduction to gretl
Applied Economics
Dali Laxton
14.10.2022
1 / 42

Outline
1   What is gretl?
2
gretl Basics
3
Importing Data
4
Saving as gretl File
5
Running a Script
6    First Exercises
7
Commands on Datasets
8
Commands on Variables
9
Graphs
2 / 33

What is gretl?
What is gretl?
gretl is an acronym for Gnu Regression Econometrics and
 Time-series Library
it is free econometrics software
it has an easy Graphical User Interface (gui)
it runs least-squares, maximum-likelihood, systems estimators...  it outputs results to several
formats
very important for us in this course: it admits scripts (sequence of  commands saved in a file)
1 / 42
3 / 33

What is gretl?
How do I get gretl?
Handy for remote learning since it is open-source free software anyone can install it on home
desktop without the need of license
In order to install it go to:
http://gretl.sourceforge.net
It runs on Windows, Mac, Linux
2 / 42
4 / 33

Installation
Open the webpage and go down where Download section is located. Click on the circled button for
windows users
5 / 33

Installation
Choose the .exe file which is appropriate for your system
6 / 33

Installation
Run the .exe file and choose default options to proceed. Do not forget to add gretl directory to
your PATH
7 / 33

Start gretl
To start gretl you can just type gretl in your search button. Select it and an empty gretl window
will pop out. You can either run commands directly in the gretl console or write scripts and save
them for future use
Gretl console
Gretl scripts
8 / 33

What is gretl?
How do I work with gretl?(1/2)
the easiest way for beginners is by using its graphical user interface
you can also use the console button of the toolbar: from the prompt  (?) you can execute gretl
commands one line at a time.
the most efficient way is by using scripts:
1
2
3
4
3 / 42
create a script file, write gretl commands one every line, and save it  run the script using the
gui
inspect output
if needed, change script file, save it, and go back to step 2
9 / 33

Running commands in the script
Click CTRL + R or click the button shown below. The window with outputs (or errors) will open. If
you save these scripts, it will be saved as .inp file.
10 / 33

What is gretl?
How do I work with gretl?(2/2)
you know your way using the gui, but want to know about scripts...
1
2
3
gretl comes with over 70 practice scripts
the manual gives good advice and devotes several chapters to provide  good programming solutions
this course will provide you with tested scripts
4 / 42
11 / 33

Opening datasets
qGretl comes with inbuilt datasets which you can play with
qGo File -> Open data -> Sample file and this will give you lots of datasets, or alternatively, go
to specific data file which you want to access in your computer by choosing User file instead of
sample file
12 / 33

Opening datasets
qIf you want to open file which has a different extension, for example excel, when you go to User
File, do not forget to set it for excel searching, otherwise nothing will be shown in the window
13 / 33

Opening datasets
qFor now let’s open a Sample file the very first one offered ‘abdata’ by double-clicking it with a
mouse
14 / 33

Playing with data
The following window will pop out. You can now check the values of each variable by double clicking
them. You can edit them etc.
15 / 33

Operations on variables
qSee summary statistics of variables by highlighting them and clicking Variable -> summary
statistics in the upper panel
qChange values of variables by highlighting it and clicking Data -> Edit values
16 / 33

Saving as gretl File
Saving as a new gretl File
You can open any other type of file using gretl (excel), do some operations on them and then save
as a gretl file (.gdt) by clicking: File ->Save Data as ->Standard format
17 / 42

Running a Script
Looking at the Session Script
Tools > Command log displays the operations that we have done so far
18 / 42

Running a Script
More on scripts
using File/Script files/New script you open the command script editor
If you have a very long command that exceeds one line, use the  backslash (\) as a continuation
command
using scripts (and the console) requires you to use the correct  language syntax
gretl's language is case sensitive: gretl considers x to be different  from X
you can find all the commands in the gretl command reference after clicking Help -> command
reference
at the console window, you can type help
19 / 33

First Exercises
Exercise 1
6
•Load the file engel.gdt. The data set contains two variables named income  and foodexp. The
variable foodexp is annual expenditures on food in a household  and income is annual income
measured in $100 increments.
•Using GUI, display logs of both variables.
•Using GUI, plot foodexp against income.
•Write all the commands in a script file and save it. Open the script and run the commands.
•Save the new dataset.
20 / 33

First Exercises
Exercise 2
The file BWGHT.csv contains information about infants' birth weight, sex  and race, the income of
their faimilies, their parents' education and the  number of cigarettes the mother smoked per day
during pregnancy (msmoke).
1
2
3
4
5
6
Import from gretl the file BWEIGHT.xlsx
Compute the average birth weight for all the babies in the sample, and  separately for boys and
girls.
Compute the proportion of mothers that smoked during pregnancy.
Which familiy variables do you think are related to children's birth  weight? Compute the
correlation among bwght and those variables.
Save the new database in gretl format.
Write down all the previous commands in a script and save it. Close  your session, open the script
and run all the commands together.
21 / 33

summary bweight –simple
smpl gender –dummy
smpl gender=0 --restrict
smpl –full
smpl msmoke=0 –restrict
Corr bweight medu

First Exercises
Basic commands for data management (1/2)
Commands on the entire data
open: opens a data file replacing any data file already open  smpl: defines the sample range
dataset: sorts/clears/transposes/adds observations and more
setobs: declares the structure of the data (cross-section, time-series,  panel)
append: appends the content of a data to the current dataset  store: saves the data into a file
22 / 33

First Exercises
Basic commands for data management (2/2)
Basic commands on variables  genr: creates a new variable  delete: removes variables
setinfo: sets attributes of a variable  rename: renames a variable
summary: shows summary statistics for variables  print: lists the values of variables
23 / 33

Commands on Datasets
smpl (#start #end | condition −−restrict | # −−random |  full) −−replace −−balanced
condition −−restrict: restricts the sample to observations that satisfy  the condition
# −−random: # cases are ramdomly selected  full: restores the full data range
sample restrictions are by default cumulative: −−replace turns off all  previous restrictions
Examples (using Example2.xls)
smpl YEAR!=1976 −−restrict
smpl EMP > 3 −−restrict −−replace  smpl 50 −−random
24 / 33

Commands on Datasets
dataset (addobs # | transpose | sortby varname | resample  # | clear)
addobs: adds extra observations at the end  transpose: transposes current data set.
sortby: sorts data by varname (dsortby: descending order) (a list of  variables can be provided;
available only for undated data).
resample: random sampling (Constructs a new dataset by random
sampling, with replacement, of the rows of the current dataset. The  original dataset can be
retrieved via the command smpl full).
clear: clears out current data
Examples
dataset sortby EMP  dataset resample 500  dataset clear
25 / 33

Commands on Datasets
setobs unitvar timevar −−panel-vars
imposes a panel interpretation
sorts data as stacked time series, by ascending values of unitvar
Examples
setobs 1 1 −−cross-section
setobs 20 1:1 −−stacked-time-series  setobs unit year −−panel-vars
26 / 33

Commands on Datasets
append newdata −−time-series
opens a data file and appends the content to the current dataset  First case: additional
observations for existing variables
Second case: new variables (best if #obs compatible)  Third case: appends a time series in a panel
First Case
open C:\there\Example2.xls −−sheet= first100  append C:\there\Example2.xls −−sheet= moreunits
appends worksheet moreunits from C:\there\Example2.xls
Second Case
append C:\there\Example2.xls −−sheet= wages  appends worksheet wages from C:\there\Example2.xls
27 / 33

Commands on Datasets
store data le [varlist] −−gzipped −−overwrite
by default data saved in gretl format
also exports to csv (using −−csv) and other formats
store C:\there\mydata.gdt
saves current data to C:\there\mydata.gdt
28 / 33

Commands on Variables
[genr] newvar = formula
a formula is a well-formed function of variables
the range over which the result is written depends on the current  sample
arithmetical operators: ^, *, /, + , -
boolean operators: ! (negation), && (AND), || (OR), >, <, =, >= ,
<= , !=
look at the gretl Function Reference (Help/Function Reference) for  built-in functions
Examples
genr y = 3 + 2 * x1 + 5 * x2 + error  D1976 = (YEAR = 1976)
genr avgy = mean(y)
29 / 33

Commands on Variables
delete [ varlist ] −−db
removes listed variables
if no varlist is given, it deletes the last (highest numbered) variable  from the dataset
−−db: deletes variables from a gretl database
30 / 33

Commands on Variables
rename varname newname
changes the name of the variable
names must be of 15 characters maximum  they must start with a letter
they must be composed of only letters, digits, and the underscore  character
Example in bwght.gdt
rename bwght birth_weight
31 / 33

Commands on Variables
summary [ varlist ] −−simple −−by=byvar
prints summary statistics for variables in varlist
if varlist is omitted, it prints statistics for all variables
−−simple: only prints the mean, minimum, maximum and standard  deviation
−−by=byvar: statistics are printed for sub-samples defined by the  values taken on by byvar
Example in bwght.gdt  summary bwght
summary bwght −−simple
summary bwght −−simple −−by=male  summary bwght −−simple −−by=parity
32 / 33

Commands on Variables
print [varlist] −−byobs −−no-dates
prints the values of the variables in varlist
if no list is given, prints the values of all variables
−−byobs: data are printed by observation, not by variable  you can also print strings
Examples
print bwght male −−byobs  print bwght ; male −−byobs :  print "This is a comment"
33 / 33