Any “estimate” is just that, an “estimate” based on whatever method the party doing the estimation employed. The estimate may either be close to the actual (truth) or far away from it depending on the method used. This applies for the population as well.
Population estimates are based on methods used by Demographers (generally) in the estimation. Population estimates should never be taken to mean actual or factual. The only factual or rather close to factual will be the census figures (i.e. depending on how credible the census operation is) which we will know after the census is done. Without the Census, we can only project or estimate.
PNG needs the Census to be done next year as planned and not delayed further. So, we can know the actual population (or close to actual) for policy and planning purposes. For example, population data is needed to calculate per capita GDP; unemployment rate; employment figures; death rate; population density; incomes; and so forth. Population data is also necessary to plan for the provision of public goods and services such as
schools and health facilities, water, electricity, etc.
So, do we know the population of Papua New Guinea? The obvious answer is no, in the absence of a recent or current census. But estimates are available, which as mentioned above, are subject to methods employed. The recent UNDP estimate of PNG’s population of 17 million has caused a stir and debate among researchers, academics and public officials and politicians.
The NRI estimate of the PNG population for 2022 is 9,422,000 (McMurray and Lavu 2020), which as the authors put it, is conservative. So, the actual population is most probably above the 9.4 million estimate. But how far above that? We will have to wait for the census.
A look at past censuses could shed some light. In 1980, the population was 2,881,933. It grew by 25.2% to 3,607,954 in 1990 and by 43.9% to 5,190,786 in 2000 and by 40.2% to 7,275,324 in 2011. NRI’s estimate of 9.422 million is a growth of 29.5% from the 2011 population. The UNDP’s estimate of 17 million is a growth of 133.7% from the 2011 population. Is one of these estimates correct and the other wrong? Not really. Both are just estimates.
However, based on the growth rates between past population periods, my inclination is that the population for PNG is between these two estimates but perhaps closer to 9.4 million than 17 million. But the 2023 Population Census cannot come soon enough so, we can know the actual or close to actual for policy and planning purposes.