Stata

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Stata
Stata logo.gif
Stata on Windows
Stata 11 on Windows
Original author(s) Bill Gould
Developer(s) StataCorp
Initial release 1985
Stable release 11.0 / July 27, 2009; 6 month(s) ago (2009-07-27)
Written in C
Operating system Windows, Mac OS X, Unix, Linux
Type statistical analysis
License proprietary
Website www.stata.com

Stata is a general-purpose statistical software package created in 1985 by StataCorp. It is used by many businesses and academic institutions around the world. Most of its users work in research, especially in the fields of economics, sociology, political science, and epidemiology.

Stata's full range of capabilities includes:

  • Data management
  • Statistical analysis
  • Graphics
  • Simulations
  • Custom programming

The name "Stata" is a portmanteau of the words "statistics" and "data"; it is not an acronym and therefore should not appear with all letters capitalised (i.e. as STATA).[1] There is no correct way to pronounce "Stata", any of "Stay-ta", "Sta-ta" or "Stah-ta" are considered acceptable.[2]

Contents

[edit] User interface

Stata has always emphasized a command-line interface, which facilitates replicable analyses. Since version 8.0, however, Stata has included a graphical user interface which uses menus and dialog boxes to give access to nearly all built-in commands. This generates code which is always displayed, easing the transition to the command line interface and more flexible scripting language. The dataset can be viewed or edited in spreadsheet format, but this must be closed before other commands are executed.

[edit] Data structure and storage

Stata can only open a single dataset at any one time. Stata holds the entire dataset in (random-access or virtual) memory, which limits its use with extremely large datasets. This is mitigated to some extent by efficient internal storage, as there are integer storage types which occupy only one or two bytes rather than four, and single-precision (4 bytes) rather than double-precision (8 bytes) is the default for floating-point numbers.

The dataset is always rectangular in format, that is, all variables hold the same number of observations (in more mathematical terms, all vectors have the same length, although some entries may be missing values).

[edit] Data Format Compatibility

Stata can import data in a variety of formats. This includes ASCII data formats (such as CSV or databank formats) and spreadsheet formats (including various Excel formats).

Stata's proprietary file formats are platform independent, so users of different operating systems can easily exchange datasets and programs. Stata's data format has changed over time, although not every Stata release includes a new dataset format. Every version of Stata can read all older dataset formats, and can write both the current and most recent previous dataset format, using the saveold command[3]. Thus, the current Stata release can always open datasets that were created with older versions, but older versions cannot read newer format datasets.

Stata can read and write SAS XPORT format datasets natively, using the fdause and fdasave commands.

Some other econometric applications, including gretl, can directly import Stata file formats.

[edit] Extensibility

Stata is unusual among commercial statistics packages in allowing user-written commands, distributed as so called ado-files, to be straightforwardly downloaded from the internet which are then indistinguishable to the user from the built-in commands. In this respect, Stata combines the extensibility more often associated with open-source packages with features usually associated with commercial packages such as software verification, technical support and professional documentation. Some user-written commands have later been adopted by StataCorp to become part of a subsequent official release after appropriate checking, certification and documentation.

[edit] User community

Stata has an active email list (Statalist, over 1000 messages per month), to which StataCorp employees regularly contribute. Statalist is maintained by Marcello Pagano, Harvard School of Public Health not by StataCorp itself. Articles about the use of Stata and new user-written commands are published in the quarterly peer-reviewed Stata Journal. User group meetings are held annually in the USA, the UK, Germany and Italy, and less frequently in several other countries.

[edit] Example Stata code

To perform logistic regression of y on x:

logistic y x

To display a scatter plot of y against x restricted to values of x below 10:

scatter y x if x < 10

[edit] Timeline of releases

In recent years, StataCorp have released a new major release of Stata (incrementing the integer part of the version number) roughly every two years. Users must pay a fee if they wish to upgrade to the latest major release. Minor releases (incrementing the decimal part of the version number) are sometimes made available in between major releases. These are available as free downloadable updates to those who have a licence for the previous major release. Dates of all releases are available on the Stata website[4]. Stata's version control system is designed to give a very high degree of backward compatibility, ensuring that code written for previous releases continues to work. Stata 11 shipped on July 27th 2009.

[edit] See also

[edit] References

  1. ^ What is the correct way to write ‘Stata’?
  2. ^ What is the correct way to pronounce ‘Stata’?
  3. ^ Stata's 'help' entry for the save command
  4. ^ History of Stata

[edit] External links

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