Estimating the density of a distribution from a finite number of data points is an important tool in the statistician's and data analyst's toolbox. In their recent paper, Bernacchia and Pigolotti (JRSS-B, 2011) introduce a new non-parametric method for the density estimation of univariate...

This paper seeks to advance our understanding about the impact of unemployment on fertility. From a theoretical perspective, both negative and positive effects might be expected. Existing empirical studies have produced contradictory results, partly because of varying institutional contexts, the...

Estimating a continuous density function from a finite set of data points is an important tool in many scientific disciplines. Popular nonparametric density estimators include histograms and kernel density methods. These methods require the researcher to control the degree of smoothing inherent...

Gaussian integration can be used to obtain surprisingly accurate evaluations of definite integrals with as few as 10 or 20 function evaluations. In this presentation, it will be shown how to incorporate tables of Gaussian integration weights into Stata data sets and use them to evaluate...

Stata's graphics are more flexible than many realise. We will exploit this flexibility and explore a potpourri of topics, some of interest to all graphers and others primarily of interest to those creating highly customised graphs or new graph commands. Among the topics will be creating custom...

We describe Stata macros that implement the composite link approach to missing data in log-linear models first described by David Rindskopf (Psychometrika, 1992, V57, 29-42). When a missing value occurs among the variables that form a contingency table, the resulting observation contributes to...

It is fairly simple to add an interaction term (also known as “effect modification” to epidemiologists) to a linear or logistic regression model, and test whether that term is statistically significant. However, it is much more difficult to explain what a significant interaction means in an...

Restricted cubic splines (RCSs) are used with generalized linear models and other regression methods to model complex non-linear relationships. A RCS with k knots is linear before the first and after the last knot, is a cubic polynomial between adjacent knots, and is continuous and smooth. A RCS...

An article in The Lancet discussed a clinical trial of a product for a rare disease. The authors had modified the primary analysis from an unadjusted Wilcoxon rank sum test to a Poisson regression. This led to several questions including: Was a Poisson distribution appropriate? How were the...

The University of Utah's Public Health Program, housed in the Department of Family and Preventive Medicine, uses Stata to supplement the core course, "Introduction to Biostatistics, I". All MPH/MSPH students are required to enroll in the lab component of the Biostatistics course wherein Stata is...