The line attributed by Mark Twain to British PM Benjamin Disraeli that there are “lies, damned lies and statistics” might be held to be true when assessing the value of indicators. Indicators, after all, only indicate, so there is scope for debate about the meaning of the UNDP’s Human Development Index, identified by Robert Johnson here yesterday and by me last Friday.

But as well as damned lies and statistics, there are also category errors — analysing metaphorical tangerines when one is supposed to be looking at oranges. They are similar, but not quite the same and confusing one for the other can lead to inaccuracies.

Johnson correctly identified the principle purpose of the UNDP’s Human Development Index is to show whether and where developing countries are improving or otherwise. However, in his response to my article, he got wrong one basic and fairly important fact: my reference was not to the UNDP’s Human Development Report 2010 but to the UNDP’s Worldwide Trends in the Human Development Index 1970-2010. It helps to pay attention to such detail.

This document unambiguously shows that Norway is now ranked No.2 in the world, with a composite score of 0.929, while Australia is ranked No.1 with a score of 0.938.

As noted in the Worldwide Trends document, it intentionally identifies “top mover” countries that have improved most in HDI terms since 1970. Australia is, to use that language, the “toppest” mover, hence last Friday’s article — that and it’s sometimes nice to take a break to temporarily feel OK about yourself.

The Worldwide Trends document uses the original human development indicators for health, education and income, identified by Johnson. But it also employs recently introduced indicators, of which there are 10 main categories, each broken down into sub-sections. Despite Johnson’s rejection of my reference to the HDIs “complex range of factors”, it is reasonable to suggest that 39 separate measurements do provide a fairly complex method of analysis.

One can debate the source of sub-Saharan Africa’s problems and AIDS has certainly been a scourge of massively epidemic proportions. But the failure to adequately deal with the AIDS epidemic in a timely manner is a consequence of poor education, poor governance and poverty.

Not seeing the links between a range of low HDIs is part of why there continues to be low levels of development. Hence, as many NGOs in developing countries point out, if Western aid workers were as expert as they present themselves, then why is so much of the world still experiencing such dire poverty more than a half a century and many billions of dollars after they started to tackle the issue?

On this, noted Africa specialist Alex de Waal has written extensively and highly critically of the aid/development industry in Africa. He has also identified the link between AIDS, poverty and, as a source of poverty, drought.

Johnson and I agree that life for many in sub-Saharan Africa is abysmal and that Zimbabwe is at the bottom of the global list, largely for reasons of absolute poverty. But Johnson’s unrealistically optimistic claim that ‘There is even a chance that Zimbabwe’s HDI is on the rise: improving in 2010 more than any of the other 168 countries’ is, to quote Jeremy Bentham, ‘nonsense on stilts’.

Zimbabwe’s HDIs peaked in the late 1980s and have been in decline ever since. Zimbabwe has, according to the Worldwide Trends, had the lowest HDIs in the world since just after 2000. By 2010, there was a yawning 50% gap to the Congo, which had the second lowest HDIs. Zimbabwe’s continuing trend was down, not up.

And unequal income distribution is not well concealed, as Johnson claims. The Gini Coefficient, which shows income distribution gaps, is one of the more important of the “complex” of human development indicators.

I am sure that the main intent of Johnson’s article was trying to draw further attention to the plight of many in the less and least developed world, which was not my main purpose last Friday but with which I agree. But in doing so, he has mis-read a few fairly important points. Not spelling my name correctly was the least important of them, but it was perhaps symptomatic.