Speaking Stata: Problems with lists

Various problems in working through lists are discussed in view of changes in Stata 8. for is now undocumented, which provokes a detailed examination of ways of processing lists in parallel with foreach, forvalues, and other devices, including new, concise ways of incrementing and decrementing macros and evaluating other expressions to do with macros in place. New features for manipulating lists held in macros and the new levels command are also reviewed. Copyright 2003 by Stata Corporation.lists, for, foreach, forvalues, levels, macros, tokenize

Circular statistics in Stata, revisited

Circular data are a large class of directional data, which are of interest to scientists in many fields, including biologists (movements of migrating animals), meteorologists (winds), geologists (directions of joints and faults), and geomorphologists (landforms, oriented stones). These examples are all recordable as compass bearings relative to North. Other examples include phenomena that are periodic in time, including those dependent on time of day (in biomedical statistics: hospital visits or times of birth) or time of year (in applied economics: unemployment or sales variations). The analysis of circular data is an odd corner of statistical science that many never visit, even though it has a long and curious history. Moreover, it seems that no major statistical language provides direct support for circular statistics. This talk describes the development and use of some routines that have been written in Stata, primarily to allow graphical and exploratory analyses. In 2004, such routines are being rewritten, especially to allow use of the new graphics of Stata 8.

Speaking Stata: Graphing categorical and compositional data

A variety of graphs have been devised for categorical and compositional data, ranging from widely familiar to more unusual displays. Both official Stata commands and user-written programs are available. After a stacking trick for binary responses is explained, bar charts and related displays for cross-tabulations are discussed in detail. Tips and tricks are introduced for plotting cumulative distributions of graded (ordinal) data. Triangular plots are explained for threeway compositions, such as three proportions or percentages. Copyright 2004 by StataCorp LP.graphics, categorical data, binary data, nominal data, ordinal data, grades, compositional data, cross-tabulations, bar charts, cumulative distributions, logit scale, catplot, tabplot, tableplot, distplot, mylabels, triplot

Analysing circular data in Stata

Circular data are a large class of directional data, which are of interest to scientists in many fields, including biologists (movements of migrating animals), meteorologists (winds), geologists (directions of joints and faults) and geomorphologists (landforms, oriented stones). Such examples are all recordable as compass bearings relative to North. Other examples include phenomena that are periodic in time, including daily and seasonal rhythms. The analysis of circular data is an odd corner of statistical science which many never visit, even though it has a long and curious history. Perhaps for that reason, it seems that no major statistical language provides direct support for circular statistics, although there is a commercially available special-purpose program called Oriana. This paper describes the development and use of some routines which have been written in Stata, primarily to allow graphical and exploratory analyses. They include commands for data management, summary statistics and significance tests, univariate graphics and bivariate relationships. The graphics routines were developed partly with -gph-. (By the time of the meeting, it may be possible to enhance these using new facilities in Stata 7.) Collectively they offer about as many facilities as does Oriana.