The State of the world population: 2004 report that is being released today suggests that life expectancy at birth for South African males in 2004 is 45.1 years while the life expectancy for females is reported as 50.7 years. The total population is estimates to decline from 45.2 million in 2004 to 40.2 million in 2050. Other estimates provided include at TFR of 2.61 and HIV prevalence rates for the sexually active population of 18.1 for males and 23.5 for females. It is also stated that the South African GDP may decline by 17% by 2010. This raises several issues that warrant discussion with the Department of Social Development about some of the assumptions and assertions in the report.
The difference between the estimates provided in the report and the official estimates by Stats SA may be largely explained by differences in the base populations used to derive these estimates. The use of the wrong base population then often leads to incorrect and often implausible estimates.
With regard to estimates of life expectancy, the official figure released by Stats SA in July this year estimated male life expectancy in South Africa for 2004 as 50 years and female life expectancy at 53 years.
With regard to mortality and HIV prevalence rates, it is the view of Stats SA that the position taken in the report is not accurate. Data form the 2001/2 Zambian DHS suggest that adult HIV prevalence rates based on ANC data may overestimate prevalence rates by as much as 20 per cent. Stats SA have estimated the HIV prevalence rate at 15,6% for 2002. This figure is based on the Nelson Mandela/HSRC study on HIV. Many demographers accept this study as providing reasonable estimates of HIV prevalence rates at the national level.
While there remains uncertainty about the level and age pattern of mortality, including non-AIDS mortality in South Africa, the estimated proportion of registered deaths is substantially higher now than at the beginning of Democracy. For 1996 Stats SA estimated the level of completeness of death registration at 67%. These substantial improvements in death registration greatly reduce uncertainty in the levels and age patterns of non-AIDS mortality.
Based on empirical evidence, the Stats SA estimates of HIV prevalence rates, are therefore approximately 6,5% lower than some International agencies such as WHO, and the United Nations. As the national statistical agency, the organization focuses on issues in an unbiased way. At present, there is no compelling empirical evidence to suggest that the Stats SA assumption of HIV prevalence should be revised. HIV prevalence rates may be revised on the completion of the causes of death currently underway.
The report provides estimates about fertility that is incorrect. The future course of fertility in South Africa is extremely important. Variation in fertility assumptions makes much more difference in estimates and projections than does variation in mortality assumptions. Fertility is important because every person is born at age zero and contributes directly to population size. Furthermore, each birth adds to the base population, which in turn contributes to population momentum and has the opportunity to pass through the reproductive ages (15-49) and have children. The estimating total fertility rate of 2.6 is too low. Extensive analyses by demographers of the 1998 DHS and the 1996, and 2001 censuses suggest that the TFR for 2001 was between 2.84 and 3.0. On the basis of this analysis Stats SA has estimated the TFR for 2004 at 2.77. The implied momentum of fertility decline suggested by the report is therefore problematic.
The report further suggests a depopulation of South Africa. It is estimated that the population will decline from 45.2 million in 2004 (approximately 1,4 million less than the official estimate from Stats) to 40.2 million in 2050 (presumably as a result of HIV mortality). It must be pointed out however, that mortality has much less effect on population growth. So, for example, when a person dies after the reproductive ages, her lifetime fertility us unaffected, or slightly affected if she dies during the reproductive ages. Neonatal and peri-natal mortality has no effect on population growth. In addition, as has been pointed out by demographers (Anderson 2002) that in virtually all populations, even very high mortality populations, the probability of dying between age 10 and age 20 is very low. It is the range of the fertility assumptions used in population estimates that are likely to be the most important element of the future size of the South African population. The implausibly low TFR of 2.6 therefore results in estimates of the total population that suggests depopulation.
A serious assertion made in the report is related to GDP. In Chapter 8 (page 64) it is stated that by one estimate if 15% of the population is HIV positive, DGP declines by 1% per year. Based on this assumption, the report argues that South Africa's GDP is expected to decline by 17% by 2010. While Stats SA is not downplaying the importance of the impact of HIV and the response needed to contain the disease, this assertion is unfounded. This statement makes in our view incorrect assumptions about the age structure of the South African labour market and the composition of those affected by HIV. It implies that 15% of the population contributes to 1% of the GDP. It is not stated in the report how this relationship is derived at. Analyzing GDP and the economy must be done in the context of the different factors and sectors of the economy's contribution to GDP. Clearly it is implausible to assume that all HIV positive persons in the workforce will fall sick at one. It is not clear at all from the report how the 15% HIV positive rate translates to a 1% reduction in GDP. However, apart from problems of this implied causal connection between reduction in GDP and proportion of the population that is HIV positive, the report also does not make explicit why this particular estimate or assumption is used.
In conclusion, the extreme assumptions of HIV prevalence rates, the associated mortality rates and the implied impact of HIV on South African society, suggested by the report are questioned. It is the position of Stats SA that these are not accurate and that they seriously distort the demographic and economic indicators of the country. The measures presented in the report do not confirm official estimates by Stats SA. However, not only are these indicators at variance with the official estimates, such as the mid-year estimates and other analysis carried out by the statistical agency, they are deemed implausible.