A Brief Introduction to Stata1

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A Brief Introduction to Stata(1)
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1. Getting Started
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• 1.1 Starting STATA
• 1.2 Running Stata
• 1.3 Open and Save Datasets in Stata
• 1.4 Exiting STATA
• 1.5 Getting help and information
• 1.6 Notes on STATA Commands
• 1.7. Entering Data into STATA

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1.1 Starting STATA

• Start a STATA session by performing either of the
  following three procedures
• double-click the STATA icon in your desktop.
• find the STAR button .
• Use Windows Explorer to navigate across the
  STATA8 folder and find the button of the
  executable file named wsestata. Double click on
  this button.

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STATA windows

• Stata Command
• Stata Results
• Review
• Variables

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1.2 Running Stata

• A command may be typed in the Stata Command
  window and executed by press the Enter key.
• Stata running can be interrupted by holding down
  Ctrl and pressing Pause/Break key.

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• It is good to open a log_file, press the button
  or use .log using filename. When you want to
  close the file,use .log close.
• Append onto the end of the current log. Type
• .log using myses, append.
• Discard the old log and replace it with the new
  one. Type
• .log using myses, replace.
• The first choice is probably the best.

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• You can find out what directory you're in by
  typing
• . pwd
• F\StataStuff
• If you wanted to make a dirctory on the F drive
  using Stata, type
• . cd F\
• F\

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Do-file

• Do-file editor
• Running do-file
• Button
• Do dofile

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Data editor

• Data Browser
• Data Editor
• Rows represent obserbvation.
• Columns represent variables.

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1.3 Open and Save Datasets in Stata

• Stata has its own data format with default
  extension .dta .

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Open a data file

• If the file is in the current directory,
• .Use filename
• If the data are not stored in the current
  directory,
• .use c\user\data
• Or
• .use c\user\data,clear
• In the first form, use filename says to load the
  data, but Stata will refuse if (1) there is
  something in memory and (2) that something has
  not been saved on disk.

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• If the memory allocated to STATA (which is 1,000K
  or 1M by default) is too little for the data file
  to be opened we will see an error message like
  the following
• . use hh
• no room to add more observations
• r(901)
• The following commands allocate 30M to STATA and
  then tries again to open the file
• . set memory 30m
• . use hh
• If you continue to get an error message, you can
  try 40m or 50m.

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• Another important thing to remember is that the
  memory allocation command (set memory 30m for
  example) works only if no data set is open.
  Otherwise you will get following error message
• .use hh
• .set memory 30m
• no data in memory would be lost
• r(4)
• You can clear the memory using one of the two
  commands clear or drop _all.

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Save a data file

• To save, type
• . save 1998Data
• . save 1998Data, replace
• . Save,replace
• Without the replace option, the file must not
  already exist. If it does, Stata will refuse to
  overwrite it.
• With the replace option, the file may exist or
  not. If the file does exist, it will be
  overwritten.

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• .cd c\user\data
• .use bank
• .save bank

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1.4 Exiting STATA

• Stata may be exited in three ways
• Click into the Close button
• Select the File menu from the menu bar and select
  Exit
• Type. Exit or . exit, clear in the Stata command
  windows and press return.

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• if you have an unsaved data set open, STATA will
  issue the following error message
• . exit
• no data in memory would be lost
• r(4)
• To remedy this problem you can save the data file
  and then issue the exit command. If you really
  want to exit STATA without saving the data file
• . exit, clear

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1.5 Getting help and information

• Stata's help system consists of two commands
• 1) .help
• 2) .search
• You use help when you know the name of the Stata
  command on which you want information. This
  command only works if you type the full command
  name or keyword unabbreviated.

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• If you can not recall the full command name or
  keyword, or you are not sure about which command
  you want you can use the command lookup or search
  followed by the command name or keyword.
• . search mem
• The STATA website (http //www.stata. com) has
  excellent help facilities, for example, Online
  Tutorial, Frequently Asked Questions (FAQ), etc.

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1.6 Notes on STATA Commands

• STATA commands are typed in lower case.
• All names, including commands or variable names,
  can be abbreviated as long as there is no
  ambiguity.
• e.g.
• .describe
• .des

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• To display the previous command in Stata Command
  window, you can press Page-Up key. You can keep
  doing that until the first command of the session
  appears. Similarly, the Page-Down key displays
  the command that follows the currently displayed
  command in the Stata Command window.

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1.7. Entering Data into STATA

• the simplest way is to enter data directly into
  STATAs spreadsheet-like Data Editor window.
• The nineth button
• . edit
• Note that data from spreadsheets can also be
  copied and pasted into the Editor.

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• you can entering data variable-by-variable with
  the TAB key or observation-by-observation with
  the ENTER key.
• a missing value is coded as a period .
• numerical values should not include commas
  otherwise STATA considered these values as
  string.

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• string variable values can nearly be almost any
  combination of letters, numbers, and symbols up
  to 80 characters in length for Intercooled/ Small
  and up to 244 characters in length for STATA/SE.
• http//www.ats.ucla.edu/stat/stata/how_to_get_stat
  a.htm
• variable names can be changed by double clicking
  anywhere in the variables column resulting in a
  dialogue box. It is suggested that variable
  names should have 8 characters.

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Reading different types of datafile

• Using Stata transfer
• Other ways
• read data into STATA from ASCII files and
  worksheets, We can use the infile command
• . cd c\intropov\data
• . infile domain hcn age using try.txt

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• use the infix command
• . clear
• . infix domain 1 hcn 2 age 3-4 using try2.txt
• Excel worksheets such as the .xls file can also
  be read into STATA. However, we have to first
  read the file with Excel, and convert the file
  into a comma-delimited file, i.e., click on File,
  Save AS, and choose as file type CSV. Then,
  enter
• . insheet using filename.csv, clear

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Review

• Ctrl Pause/Break
• .log using myses, append
• . pwd
• . cd F\
• use c\user\data,clear
• set memory 30m
• . save 1998Data, replace
• . Save,replace

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• . exit
• .help
• .search
• .describe
• .des
• .edit
• .infile
• .infix
• .insheet