MP Gammanpila messes up the math on demographic change

Fact Check

In the above statement, MP Gammanpila makes two claims: that (i) the Muslim (Sri Lankan Moor) population will exceed 12% of the total population in the next 10 years (i.e. by 2029); and (ii) the Sinhala population is declining and is under threat of extinction by the rapid growth of the Muslim population.

The MP’s claim is based on the growth of the Sri Lankan Sinhalese and Moors, in the under 5 age group (born during 2008-2012) relative to the 5-9 age group (born during 2003-2007).

This fact-check uses the data and basis presented by the MP to determine if his claim can be substantiated. That means it overlooks some small discrepancies in the MP’s data vs. published statistics (see Exhibit 2); and ignores concerns about the MP’s methodological approach – which has received significant discussion in the media.

Based on precise numbers given by the MP, the growth rates for the 5-year cohort, born in 2008-2012 compared to 2003-2007, are 0.48% and 1.43% for the Sinhala and Moor populations respectively. This rate of growth of the five-year cohorts for the Sinhala and Moor population are equivalent to a growth in annual births, relative to the births in the previous year, of 0.096% and 0.284% respectively. An annual population death rate of 0.6% was applied based on last available census data. FactCheck used these parameters to calculate the Sinhala and Moor population growth post-2012 on the basis of the MP’s claim, as shown in Exhibit 1. The growth of other populations was set at zero, which most favours the MP’s claim.

This calculation, on the MP’s own data and basis, results in the Moors accounting for 12% of the total population only in 50 years (in 2069) and not in 10 years (in 2029) as the MP claimed, even with zero growth in the rest of the population.

Further, the math, on the MP’s data and basis, does not allow for the Sinhala population becoming extinct, as the MP claims. It results in the Moor population even catching up to the size of the Sinhala population only in 1,063 years, that is in 3082.*

This means there is a huge mismatch between the data and basis presented by the MP, and the demographic conclusions that he derives from them.

Therefore, we classify his statement as BLATANTLY FALSE.

**FactCheck’s verdict is based on the most recent information that is publicly accessible. As with every fact check, if new information becomes available, FactCheck will revisit the assessment.

Exhibit 1: Demographic change projected on the data and basis presented by MP Gammanpila

Calculation parameters are derived from MPs data and published statistics:

(i) Annualised birth rate for the Sinhalese population: ⁵√(0.0048+1) – 1 = 0.096%

(ii) Annualised birth rate for the Moor population: ⁵√(0.0143+1) – 1 = 0.284%

(iii) The deaths as a percentage of total population from 2012 (census year) data= 122,741/ 20,359,439 = 0.60%

(iv) Population growth of other ethnic groups (i.e. except Sinhalese and Moors) is equal to zero.

Exhibit 2: Population by age cohort and ethnicity

*If instead we used the rounded off parameters reported by the MP, the duration for equalization actually increases a little to 1,111 years, that is in 3130.