Fall begins

秋天来了。天空突然变得高远而清澈。外面温度还是那么高，但是心情却由着这清明的天色而没那么烦闷了。

北京，秋天来了……

By the way, Linux is a superior platform for number crunching compared to Windows. One needs to install lots of extra stuff to have a more or less comparable working environment under Windows. This is one of reasons I am so happy after getting aML working on my Ubuntu box.

Compiling aML under Ubuntu 7.04, again!

I decided to give to it another try. I wrote to Stan, reporting the problem I had when trying to compiling aML on my Ubuntu 7.04 box. He pointed it out that it is likely to be a bug in the compiler. Then I ask myself: why not try a different compiler?

Some google search shows that alternative FORTRAN 77 under linux includes PGI, Intel, Absoft, among others. PGI offers 30 days trial, so I decided to give it a try. The pgf77 generates correct binary for "aml", "bigaml", and "hugeaml", but it creates problems for "mktab", a utility to create tabular results out of aML output files. I need to re-compile this utility using the old g77 compiler.

In short, an easy solution to the problem will be to use pgf77 to generate the main binaries and to use the g77 to generate the auxiliary binaries, then put them together in one place (in the system path).

I have checked using both the provided samples and my own data, so far so good.

Access blogpost in China

I just realize that this site can be assessed in China without using VPN or proxy. This just happened today.

More aML stuff

This software review is also a good introduction of aML: http://www.cmm.bristol.ac.uk/learning-training/multilevel-m-software/reviewaml.pdf

Dan Powers (http://www.la.utexas.edu/research/faculty/dpowers/) also has some aML-related meterials, scattering around at different places.

Fun blogs

These blogs look fun:
http://ucla-stattalk.blogspot.com/
http://www.iq.harvard.edu/blog/sss/

"Censoring Due to Death"

Interesting blog post I found: http://www.iq.harvard.edu/blog/sss/archives/2005/09/censoring_due_t_1.shtml

New data wave from CLHNS

New wave of the Cebu Longitudinal Health and Nutrition Survey is out. I need to update my data and run the Mplus program for catch-up growth and see if anything changes.

Mplus vs. aML

I am working on a joint model of miscarriage and child mortality. The idea is that higher rate of miscarriage may end up with a more highly selected newborns, who are less vulnerable to premture death. This is a Heckman selection type of model, with the exception that the main equation is a hazard model instead of a continuous model. I have been trying to make Mplus to do the job, as hinted by Bengt (http://www.statmodel.com/discussion/messages/11/740.html?1155563326). Then I got a direct response from Linda that this type of model cannot be estimated using Mplus (http://www.statmodel.com/discussion/messages/14/2459.html?1185842830). I guess this leaves me no other alternatives but to go to aML.

aML is a fine software. I used it in 2004 for a chapter of my dissertation (at that time it cost about 1,000 bucks). Now it is free and open-source, and everyone can look at the code (in FORTRAN) to see how certain things are done. I am a little surprised that it has not attracted more attention.

What I would really like to see is a wrapper program in Stata and can 1) export data to aML, 2) automatically generate sensible starting values and feed them to aML, and 3) gather coefficients estimated in aML for post-estimation manipulation.

If nobody has already started working on this, I might end up doing it myself.

LyX 1.50 is out, with unicode support

LyX 1.50 seems to be a real alternative to MS Office and OpenOffice for serious writing. Now it has unicode support built in. I have tried it on both Windows and Linux and it works jus fine. What I have not figured out is how to get the file compiled with LaTeX into DVI file correctly when there are double-byte characters (Chinese, for example).