Lots of links for you to investigation here.
When completing your task on measuring development use this data sheet - but also you can select your own data from the 2012 Data Sheet
How to correlate your data can be found here.
United Nations Human Development Index
extension...
The UK Goverment is planning to measure our happiness - how? why? - read this BBC report, follow some of the links and suggest what criteria you would use!
The Happy Planet Index - find out more...
Classifying Countries:
via chartsbin.com
Select appropriate maps from worldmapper
Visit Gapminder to look at changes in measures of development...