Expat HR Consultancy middle management compensation

I've come across an article that quoted the results of a survey in regards to the salary of expatriate workers, and I was impressed by the numbers that they highlighted.

A survey by human resources consultancy ECA International found that based on overall pay, expatriate middle managers in Hong Kong receive about US$249,814 (S$301,201) a year on average. Even though the whole compensation package includes benefits such as housing and school fees, expats there are still paid much lower than Japan’s US$351,516 (S$423,824) and India’s US$269,176 (S$324,538).

http://humanresourcesonline.net/news/28315

I always get curious about the source article once authors start throwing averages at the reader. I feel like an average could be a very deceptive interpretation of data, particularly in the case of surveys as it doesn't address the range of data. I've decided to look further into the details of the expatriate compensation by going to the source article. I have found this interesting graph that shows the components

of the compensation and their value. (Source: http://www.eca-international.com/news/press_releases/show_press_release?ArticleID=7434). I believe that the original article had made a correct suggestions to the people that may be faced with this decision, that is to do the research. Looks like the ECA-international is as good a place as any to start that research.

The results, free to participants, enable companies to benchmark their expatriates' actual salaries against the market. 234 companies took part in the survey covering 119 countries and over 10 000 international assignees.

ECA's MyExpatriate Market Pay Survey 2011 is now open. Details can be found here: http://www.eca-international.com/myeca/surveys

I am not really familiar with the actual number of expatriates to assess the appropriate population, but that sample size of 10 000 seems appropriate for a compensation survey. 
Fortunately I also found this youtube video of the rep from ECA-international talking about the survey and explaining the results.