Each year the mass media and many governments look keenly at the country rankings by the Human Development Index (HDI). In the 2010 Human Development Report, Zimbabwe has the lowest HDI in the world at 0.14 on a (0,1) scale (UNDP, 2010). The next lowest is the Democratic Republic of the Congo (DRC), with 0.24. (Norway is highest, at 0.94.)
It is natural to ask: what would Zimbabwe need to do to get its HDI up to the level of the DRC or better? Zimbabweans will no doubt have a strong interest in knowing the answer, as will those interested in the HDI in general.
There are three components to the HDI, for life expectancy, schooling and income. Let’s look at these in turn.
Zimbabwe has a life expectancy in 2010 of 47 years, the fourth lowest in the world. The new HDI puts a marginal weight on life expectancy in Zimbabwe of 0.0017. Even a 10-year increase in life expectancy would add only 0.017 to the country’s HDI. Allowing for the nonlinearity in the HDI, one finds that to get Zimbabwe from the lowest HDI to that of the DRC would require a life expectancy of 154 years! That does not sound like a promising route for reaching the next rung of the HDI ladder.
What about extra schooling? According to the 2010 HDR, mean years of schooling in Zimbabwe in 2010 was 7.2 years. Factoring in expected schooling (to form the HDI’s composite schooling measure) the number rises to 8.2 years. To get up to the DRC’s HDI by higher schooling, Zimbabwe would need to get that number up to 41 years—six years short of Zimbabwe’s current life expectancy! Schooling does not sound like a promising route either.
Zimbabweans would clearly have a much better chance of not having the world’s worst HDI by increasing their national income. I calculate that an income of $240 per person per year—about half way between Zimbabwe’s current income and that of the DRC—would be sufficient to bring Zimbabwe up to the DRC’s HDI, all other things equal. That is clearly much more feasible.
Have the HDRs changed their tune on economic growth?
Did the 2010 HDR really intend to tell Zimbabweans that their only real hope of not having the world’s worst HDI is economic growth? That they can forget about health care and schooling for now? That would be surprising, given that the HDRs have tried so hard to de-emphasize economic growth as the main measure of development success.
But there is no sign in the text of the 2010 HDR that they have changed their tune on growth. The latest report repeats past critiques of the “growth-is-enough” argument. (Though, as in past HDRs, this looks like a straw man; there has long been a fairly broad consensus that policies for promoting economic growth need to be complemented by those for promoting better health care and schooling.)
Maybe what we are really seeing here are consequences of a poorly conceived index, as I have argued elsewhere (Ravallion, 2010). These properties of the HDI stem from the methodological changes introduced in the 2010 report. In the 2010 HDR, the HDI switched from its old additive form, which uses the arithmetic mean across its three components, to the geometric mean. And the HDI’s lower bound for re-scaling income is arguably too high. The weight on longevity in Zimbabwe is driven down by the country’s low overall HDI, which is low because the country’s income happens to be very close to the HDI’s assumed lower bound for income. For the same reason, the weight on income is driven way up.
Of course, Zimbabwe is not a typical country: it has the lowest HDI. But it suffices to illustrate more generic and troubling features of this index. As I have argued elsewhere, there are systematic patterns in how the weights and tradeoffs embedded in the HDI vary across countries—patterns that are ethically troubling (Ravallion, 2010).
As the 2011 HDR team work on their report (due later this year), maybe they should reflect on whether their new HDI is sending the intended signals to countries such as Zimbabwe. If they decide that economic growth really is the overwhelming issue for Zimbabwe, and other low-income countries, then this should be argued explicitly, rather than being some implicit and (possibly) unintended consequence of how they happen to have stitched together the various components of the HDI.
Ravallion, Martin, 2010, “Troubling Tradeoffs in the Human Development Index .” Policy Research Working Paper 5484, World Bank, Washington DC.
United Nations Development Programme, 2010, Human Development Report , New York: Oxford University Press or Palgrave Macmillan for the UNDP.