Friday, August 31, 2007


It is getting cooler here in Beijing. Hopefully Hangzhou will be cool off in the next half month so that we can fully enjoy our bike trip between Hangzhou and Suzhou.

Wednesday, August 29, 2007

Stata 10 graphics editor, bad idea!

The new graphics editor provided in Stata 10, to me, is a bad idea. Instead of focusing on trying to get the figure right in a do file, many people, especially beginners, will take shortcuts and rely heavily on the new editor. This, in long run, is a very bad idea. Once people start to do that, they lose the capability to be able to replicate exactly what they do. If you spend 10 minutes editing a figure, then realize the data is not quite right and need to run the figure command again, then you need another 10 minutes to edit it... you get the idea.

It is a bit disappointing to find that unicode support is still not there. I have been waiting for this for too long...

Wednesday, August 22, 2007

aML reported random effects

The random effects that aML reports are standard deviation and correlation, not variance and covariance.

Tuesday, August 21, 2007

Age, period, and cohort effect

A model with age, period, and cohort can only be identified if:

1) Two or more of the remaining age, period, or cohort coefficients to be equal;
2) Use a proxy variable approach that assumes the cohort (e.g. cohort size) or period effects are proportional to certain measured variables;
3) Transform at least one of the age, period, or cohort variables so that its relationship to other is nonlinear.

A piecewise linear hazard rate model can usually be identified because of (3).

Friday, August 10, 2007

Ideal calender solution

The combination of Google calender, Mozilla Sunbird (or Thunderbird + Lightning), and Google calender provider ( provides an ideal calender solution. More details can be found here:

Thursday, August 09, 2007

My working paper

My most recent working paper "Does Son Preference Influence Children's Growth in Height? A Comparative Study of Chinese and Filipino Children" is available online:

Another one (impact of famine on mortality) will be available soon.

Fall begins



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.

Wednesday, August 08, 2007

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.

Tuesday, August 07, 2007

Access blogpost in China

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

Monday, August 06, 2007

More aML stuff

This software review is also a good introduction of aML:

Dan Powers ( also has some aML-related meterials, scattering around at different places.

Saturday, August 04, 2007

Fun blogs

These blogs look fun:

"Censoring Due to Death"

Interesting blog post I found:

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.