More questions on credibility of Dr Gampat’s estimates on net migration

Dear Editor,
I refer to Dr Gampat’s letter in the local media on October 14, 2024, with the caption “I reiterate the fundamental point that the difference between arrival and departure cannot serve as an estimate or substitute of net migration”.
Dr Gampat sought to defend his thesis on the methodology he utilised in his book to arrive at the net migration rate for the period 2000-2018. The goodly professor intimated that he is uninterested in part II of my essay, which I wrote on the issue citing the World Bank/UN data on net migration and expanding on the context of the argument.
With respect to his “clarifications”, I have a few questions for Dr Gampat since he’s taken the time to lend clarity on the methodology he employed in his book.
He explained that to estimate the net migration rate, he employed the “Beautiful Population Identity” method to solve for the unknown variable (net migration). To this end, he demonstrated that for the 19 years period from 2000-2018, that the country’s population fell by 25, 262.
My questions are: what is the source of his population data that showed the decline in the population for that period, when the latest official census data available was the 2012 census? Did he estimate the population for those years, and if so, what were the basis for his assumptions? It could not have been that he used the estimated population rate by the Bureau of Statistics for that period, because those estimates showed an increase in the population. Did he conduct his own house-to-house verification to derive his estimate on the population for that period? If so, please publish the report.
Dr Gampat would appreciate that the integrity of his data is as equally important as the integrity of the methodology employed, as well as the results derived therefrom. As such, Dr Gampat’s clarification on his book raises concerns about the integrity of his data source and/or method of assumption, and more so, the quality of the end result of his analysis.
I would appreciate some clarifications on these questions for the benefit of the readers.

Sincerely,
Joel Bhagwandin