(This article was first published on

Today I've given the talk on the model for structural zeros and the related R package BCEs0 for the third time in three weeks (this time it was at the London School of Hygiene and Tropical Medicine).**Gianluca Baio's blog**, and kindly contributed to R-bloggers)*Le Tour*is going quite well, I think $-$ in all three occasions, the talk has been well received. What I think is also interesting is that each time I have received a very different set of questions.

At GSK, people in the audience asked questions on the broader methodology for cost-effectiveness analysis (which they weren't probably very familiar with). In Las Palmas, most questions were about the details of the Bayesian model (for example, the use, or misuse, of the DIC as a measure of model fit and to apply structural sensitivity analysis).

Today, most questions were about the substantial aspects of the economic evaluation. For example, Richard made the interesting point that the model for structural zeros could be turned into a model for "structural ones" in the utility measure $-$ the problem being that sometimes when QALYs are used as the measure of effectiveness, a bunch of patients are associated with a value of 1, which indicates maximum utility.

This effectively generates a two-component mixture (individuals with utilities in $[0;1)$ and individuals with a utility value of exactly 1). The extension of the hurdle model should be able to do the trick in this case too. This may be a good thing to do for my undergraduate student who will do her project on health economics!

To

**leave a comment**for the author, please follow the link and comment on his blog:**Gianluca Baio's blog**.R-bloggers.com offers

**daily e-mail updates**about R news and tutorials on topics such as: visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave, LaTeX, SQL, Eclipse, git, hadoop, Web Scraping) statistics (regression, PCA, time series, trading) and more...