To test for group differences in growth trajectories in mixed (fixed and random effects) models, researchers frequently interpret the coefficient of group-by-time product terms. While this practice is straightforward in linear mixed models, testing for group differences in generalized linear...

The creation and testing of interaction terms in regression models can be very cumbersome, even in Stata 8. We propose a simple wrapping command, -fitint-, that fits any generalised linear model and tests any twoway interactions, as well as all main effects. There is no need to use -xi- because...

Among various structures in Stata for cycling through lists (whether lists of variable names, numbers, or arbitrary strings) are foreach and forvalues, introduced in Stata 7 in 2001, and for, introduced in Stata 3.1 in 1992, and revised in 5.0 (1997) and 6.0 (1999). Typically, each member of the...

A Stata program will be presented for improved quality control of econometric models. It is well known that reported econometric results often have unknown reliability because of selective reporting by the researcher. In particular, t-statistics are often uninformative or misleading when...

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...

The “fallacies of the wrong level” (e.g., ecological fallacy) are a concern in much of social-science research. When appropriate data are available, researchers frequently use intra-class correlations or ANOVAs to decide whether to use individual-level data or whether to aggregate and...

Most of the microeconometrics studies are being based on the causal inference analysis. diff provides to the researcher an easy-to-use tool to perform the difference-in-differences estimation from a two-period panel dataset designed for an impact evaluation. It combines the conditional...

This presentation shows and applies a new user-written Stata command, enhancedeba, that facilitates the extreme bounds analysis (EBA) methodologies proposed by Leamer (1983, 1985) and Sala-i-Martin (1997). This command is useful for robustness checks and determining whether relationships between...

Applied scientists, especially public health scientists, frequently want to know how much good can be caused by a proposed intervention. For instance, they might want to estimate how much we could decrease the level of a disease, in a dream scenario where the whole world stopped smoking,...

Decomposition of the goodness of fit to (groups of) regressor variables can be a useful diagnostic tool to quickly assess “relative importanceâ€. Owen and Shapley values, two closely related solutional concepts in cooperative game theory, provide unique solutions to the decomposition...