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2010 Italian Stata meeting recap

David Drukker and I just got back from the Italian Stata Users Group meeting in Bologna, arranged by TStat, the Stata distributor for Italy. It was wonderful, in part because of the beauty of Bologna, and the tasty food. The scientific committee and TStat did great jobs of selecting papers and organizing a smooth, interesting meeting.

The first day of the meeting had talks by users and StataCorp. There was good variety, with topics like investigating disease clustering, classification of prehistoric artifacts, small-area analysis, and the careful interpretation of marginal effects. This year, all the talks were in English — and it was once again amazing to see how well people can present in a second (or third) language. If you would like to see the slides which accompanied the talks, you can find them at http://www.stata.com/meeting/italy10/abstracts.html.

Recently, I have been thinking about how to interpret results from nonlinear models, so I found Maarten Buis’s talk on “Extracting effects from non-linear models” and David’s talk on “Estimating partial effects using margins in Stata 11” really useful. Both Maarten and David have thought carefully about this problem and each of them presented great introductions and easy to apply solutions. What is interesting is they favor different solutions. Maarten leaned more towards estimating and interpreting ratios that did not vary with the covariates. David recommended using the potential outcome framework which can be implemented using the margins command. The similarities and differences in these two talks made them even more informative.

As is typical for the Italian meetings, the second day had two training sessions, one given by David on programming your own estimation command in Stata (starting from the basics of Stata programming), and one given by Laura Antolini from the Università di Milano Bicocca on competing risks in survival analysis. Both courses were booked full.

I was a Stata user for 15 years before I started working at Stata, and the most fun parts of the meeting are the same now as when I was a user: the wishes and grumbles followed by the conference dinner. The wishes and grumbles session is always interesting; it shows the wide variety of approaches to using Stata. The conference dinner is always fun, because of the conversation over excellent food. In Italy, of course, the food is beyond excellent; strolling through Bologna on marble sidewalks under colonnades while talking statistics, programming and Stata made the evening, if in a intellectual fashion.

Mata, the missing manual, available at SSC

I gave a 1.5 hour talk on Mata at the 2010 UK Stata Users Group Meeting in September. The slides are available in pdf form here. The talk was well received, which of course pleased me. If you’re interested in Mata, I predict you will find the slides useful even if you didn’t attend the meeting.

The problem with the Mata Reference Manual is that, even though it tells you all the details, it never tells you how to put it all together, nor does it motivate you. We developers at StataCorp love the manual for just that reason: It gets right to the details that are so easy to forget.

Anyway, in outline, the talk and slides work like this

  1. They start with the mechanics of including Mata code. It begins gently, at the end of Stata’s NetCourse 151, and ends up discussing big — really big — systems.
  2. Next is a section on appropriate and inappropriate use of Mata.
  3. That’s followed by Mata concepts, from basic to advanced.
  4. And the talk includes a section on debugging!

I was nervous about how the talk would be received before I gave it. It’s been on my to-do list to write a book on Mata, but I never really found a way to approach the subject. The problem is that it’s all so obvious to me that I tend to launch immediately into tedious details. I wrote drafts of a few chapters more than once, and even I didn’t want to reread them.

I don’t know why this overview approach didn’t occur to me earlier. My excuse is that it’s a strange (I claim novel) combination of basic and advanced material, but it seems to work. I titled the talk “missing manual” with the implied promise that I would write that book if the talk was well received. It was. Nowadays, I’m not promising when. Real Soon Now.

The materials for all the talks, not just mine, are available at the SSC(*) and on www.stata.com. For the UK 2010, go to http://ideas.repec.org/s/boc/usug10.html or http://www.stata.com/meeting/uk10/abstracts.html. For other User Group Meetings, it’s easiest to start at the Stata page Meeting Proceedings.

If you have questions on the material, the appropriate place to post them is Statalist. I’m a member and am likely to reply, and that way, others who might be interested get to see the exchange, too. Please use “Mata missing manual” as the subject so that it will be easy for nonmembers to search the Statalist Archives and find the thread.

Finally, my “Stata, the missing manual” talk has no connection with the fine Missing-Manual series, “the book that should have been in the box”, created by Pogue Press and O’Reilly Media, whose website is http://missingmanuals.com/.

* The SSC is the Statistical Software Components archive, often called the Boston College Archive, provided by http://www.repec.org/. The SSC has become the premier Stata download site for user-written software on the Internet and also archives proceedings of Stata Users Group meetings and conferences.

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