Stata's matrix language, Mata, highlighted in Bill Gould's Mata Matters columns in the Stata Journal, is very useful and powerful in its interactive mode. Stata users who write do-files or ado-files should gain an understanding of the Stata-Mata interface: how Mata may be called upon to do one...

Data on three proportions, probabilities, or fractions that add to 1 can be projected from a simplex to the plane and represented in a two-dimensional plot, commonly known as trilinear, triaxial, triangular, etc. The Stata program triplot has been available for some years as one way to produce...

This presentation focuses on predicted probabilities for multilevel models for dichotomous or ordinal responses. In a three-level model, for instance, with patients nested in doctors nested in hospitals, predictions for patients could be for new or existing doctors and, in the latter case, for...

Google has recently developed a new tool to allow users to create Google-like charts and maps: the Google Application Programming Interface (API) chart. This tool allows the user to create custom PNG pictures by sending an appropriate syntax code over the web. Here we present two Stata programs...

In regression and multivariate analysis, the presence of outliers in the dataset can strongly distort classical estimations and lead to unreliable results. To deal with this, several robust-to-outliers methods have been proposed in the statistical literature. In Stata, some of these methods are...

PanelWhiz is a collection of Stata Add-On scripts to make using panel datasets easier. It is designed for empirically minded economists, sociologists, political scientists, and demographers and allows the user to select vectors of variables at once. Matching and merging is done automatically. It...

The purpose of this talk is to illustrate the main features and applications of two new Stata programs for spatial density estimation: spgrid and spkde. The spgrid program generates two-dimensional arrays of evenly spaced points spanning across any regular or irregular study region specified by...

Stata’s xtmixed command can be used to fit mixed models, models that contain both fixed and random effects. The fixed effects are merely the coefficients from a standard linear regression. The random effects are not directly estimated but summarized by their variance components, which are...

The design decisions made by Stata in handling missing data in relational and logical expressions have, for the user, complex, pernicious, and poorly understood consequences. This presentation intends to substantiate that claim and to present two possible resolutions to the problem. As is well...

The parmest package creates output datasets (or results sets) with one observation for each of a set of estimated parameters, and data on the parameter estimates, standard errors, degrees of freedom, t or z statistics, p-values, confidence limits, and other parameter attributes specified by the...