Stata


Stata
Stata on Windows
Stata 10.0 on Windows
Developed by Statacorp
Latest release 10.1 / August 11, 2008
OS 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" was formed by blending "statistics" and "data"; it is not an acronym.

Contents

User interface

Since version 8.0, 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.

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).

Stata's file formats are platform independent, so users of different operating systems can easily exchange datasets and programs. Additionally, in reference to Stata's datasets, Stata 10 is backward compatible with regard to Stata 8 and Stata 9, but Stata 8 and Stata 9 are not forward compatible with regard to Stata 10. In other words, Stata 10 can open datasets that were created in Stata 8 and Stata 9, but Stata 8 and Stata 9 are unable to open datasets that were created in Stata 10, unless the Stata 10 user saves with the saveold command.[1]

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.

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.

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

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[2]. 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.

See also

References

  1. ^ Stata's 'help' entry for the save command
  2. ^ History of Stata

External links


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