[ddj] Graphing Obesity (Body Mass Index >30) vs Gross National Income per capita - Feedback needed

[Roberto Belo-Rovella]

Hello, my name is Roberto Belo and I work for the BBC World Service. I
need your statistics expertise on the project we are working on.

We are looking into a set of data provided by the WHO, which we
complemented with GNI per capital (Atlas method) from the World Bank:
http://bit.ly/kF6fyr . We are just looking at the period from 1980 to
nowish, with data from 1980 (except for Russia), 1990, 2000 and 2008.

We are trying to show the relation between a higher income and the
increase in Obesity (% of population with BMI bigger than 30),
especially focusing on the G7 countries on one side, and on the BRICS
countries (Brazil, Russian, India, China, South Africa) on the other.

1) Originally we produced this graphic, showing the variation of
Obesity vs GNI per Capita, and as the variations within the years seem
to be linear, we just included 1980 and 2008 (except for Russia, we
took it from 2000) - NB Just focus on the graphic, the rest is
furniture.

<<obesity_bmi_v_gni.png>>
This shows that the increase in obesity cases have been steeper in
BRICS countries than in G7 ones.

2) This one shows Obesity vs the % variation of GNI per Capita - and
here the picture seems to change radically, with a mixed picture.

<<obesity_bmi_v_percent_increase_gni.png>>
3) Finally, this one, which shows the % variation in Obesity vs the %
variation of GNI per Capita - which I think falls into very muddy
waters, but hey, the designer was very enthusiastic

<<obesity_percent_increase_bmi_v_percent_increase_gni.png>>
Given all these, would someone be able to shed some light into which
of these three options would be the most honest and statistically
correct way of showcasing the data - and why?

Otherwise, if you could point me in the direction of someone who would
be able to make total sense of this, I would be very grateful.

We have been putting a lot of effort in getting data journalism into
the agenda, and we can't afford a mistake in this presentation.

Thanks a lot.

Roberto

Roberto Belo-Rovella | BBC WS Future Media Editorial
Room 500NE, Bush House, London WC2B 4PH
Phone: +44 20 755 70611 (Ext: 02 70611)
E-mail: roberto.belo at bbc.co.uk
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