This presentation updates Nichols and Schaffer's 2007 UKSUG talk on clustered standard errors. Although cluster-robust standard errors are now recognized as essential in a panel data context, official Stata only supports clusters that are nested within panels. This rules out the possibility of...

Circular statistics are needed when one or more variables have outcome space in the circle, which is for example true for data measured with reference to compass, clock, or calendar. Applications abound in the earth and environmental sciences, not to mention economic and medical fields well...

We introduce a Stata implementation of coarsened exact matching, a new method for improving the estimation of causal effects by reducing imbalance in covariates between treated and control groups. Coarsened exact matching is faster, is easier to use and understand, requires fewer assumptions, is...

Consistency of the maximum likelihood estimators for the parameters in the standard Tobit model rely heavily on the assumption of a normally distributed error term. The Box Cox transformation presents an obvious attempt to preserve normality when the data make this questionable. This paper sets...

Competing-risks survival regression provides a useful alternative to Cox regression in the presence of one or more competing risks. For example, say that you are studying the time from initial treatment for cancer to recurrence of cancer in relation to the type of treatment administered and...

This talk will introduce the main ideas of structural equation models (SEMs) with latent variables and Stata tools that can be used for such models. The two approaches most often used in the applied work are numeric integration of the latent variables and covariance structure modeling. The first...

Stata is a command driven program. It is a general purpose statistical software package which is used by people of different backgrounds and professional disciplines. Most STATA users, however, are non-physicians. Since it is used by people of all fields, most training programs offered are...

This presentation will show how to use of the new margins command, introduced in Stata 11, to explore interactions in regression and analysis of variance. The talk will cover three types of interactions: 1) categorical by categorical, 2) categorical by continuous, and 3) continuous by...

This presentation discusses how to store, analyze, and present Stata output. I explain how to use my commands –regsave– and –svret– to save Stata output to a Stata-formatted dataset. Results can then be easily manipulated using standard Stata commands. I next...

Several options for estimation and prediction in regressions using nonnegative skewed dependent variables are compared. Often, Poisson regression outperforms competitors, even when its assumptions are violated and the correct model is one that justifies a competitor.