Government’s decision to use an amended population estimate to determine the number of COVID vaccinations needed to reopen the border has drawn controversy, and raised questions over how it was calculated.

Now, in response to a Freedom of Information request by the Cayman Compass, the Ministry of Finance & Economic Development has made internal records available showing how and why the population estimates were amended.

The move to amend the population estimate, announced at a press conference on 16 June, increased Cayman’s estimated population by about 8%, from 65,786 to 71,106.

That had the effect of pushing the 80% ‘full vaccination’ target for Cayman’s population, which had appeared to be within reach, months into the future.

It still remains difficult to attain.

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At this stage, 50,682 residents have received at least one vaccine jab. This is approximately 6,200 people less than the number required to reach 80% under the revised population figures.

The ministry said in its FOI response that Cayman’s population had “changed immensely” since the last Census in 2010, and had also changed considerably since the last Labour Force Survey (LFS) in the fall of 2020.

During a verbal discussion on 26 May with the Economics and Statistics Office (ESO), the newly-elected government asked the ESO to validate the published population estimate of 65,786 from October 2020 and estimate the population for April 2021.

The ESO prepared a draft report for internal purposes, which pointed out that the estimated population from the Labour Force Survey contained a 5% margin of error, stating the statistics office is 95% confident the number of residents could be between 60,886 and 70,686.

The ESO recommended government should use the upper limit of 70,686 to calculate vaccination ratios.

This figure was then updated based on records of births and deaths, changes in work permits and permanent resident grants, and net migration of Caymanians, resulting in the maximum upper population limit of 71,106 now used to calculate vaccination ratios and targets.

The ESO also validated the age bands of the population. These are not normally estimated, but were last determined during the 2010 census.

The report adjusted the census data by 11 years for Caymanians, to account for the time that has past since 2010, and applied the figures from birth and death records. It also updated the age bands for non-Caymanians with current work permit and permanent residency data, including dependants.

This resulted in a lower share of the population of under 12-year-olds (12.7%) and a larger share of over 60s (12.2%) than if the age band percentages of the 2010 census had been applied to current estimates of Cayman’s total population.

EDITOR’S NOTE: In this case, the 5% margin of error refers to the number of times the population figure is expected to be larger or smaller than the given range (i.e., 1 in 20 times), not the size of the range (such as plus or minus 5%). The range of the estimate depends on the population mean, the standard deviation and a specific score (the z-score) related to the chosen confidence interval (in this case 95%). If a smaller margin of error is selected, the range of the population estimate would be wider.

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6 COMMENTS

  1. Thank you. A couple of yesterday’s questions were answered. But most remain open.

    Hope this 18th of June comment is a misquote “This has led to a revised conclusion that there is likely around 71,100 people living in the Cayman Islands,”

    No, the chart of estimates shows that the plus or minus 5% estimate of CI population is 60,886 to 70,686 and the most likely population is midway in the middle – 65,786.

    The next chart adds different groups together to show a total of 71,106.
    However, could some individuals be in more than one group?
    Are all in each category actually “in” CI?
    Also, have all Permanent Residents who left Cayman returned?
    Seems, this chart might be overcounting actual population.

    Most statistical estimates will include confidence level to indicate how reliable the numbers are, which are not shown in these charts.

    And why would the advice of economics department be followed for medical choices?

    More questions?

    Chris U

  2. 5% of 65,786 is 3,289, not 4,900. Then even after that miscalculation the total population was adjusted up AGAIN! Either someone is really bad at math or the people in charge are making up stuff to not open up!

    It is clear the government is simply making up numbers to NOT hit the 80% and then people with no math skills are making up the excuses.

    It is not that hard to count 65,000 people, It could have been done manually by now

    The decision to go with 71K – a figure higher than the pre covid peak – tells you the government is not interested in opening up and will create its own figures so that it doesn’t have to abide by its own rules.

  3. So, the entire ESO exercise, based on the age-group breakdowns (coincidentally the age groups of jab eligibility) served only to confirm that the MEDIAN population estimate remains around 65,000 people; plus or minus 5%… with 95% confidence. NOT that ESO is 95% confident that the population is actually 71,100. That is how population statistics work. You don’t take the upper-bound of an estimated range and apply that as the estimate.

    Second; it also illuminates that 12.50% of the population, whatever it really is… is 11 years and younger, and not eligible for the jab.

    In summary; of an estimated population of 65,000; 8,125 cannot be vaccinated; and of the remaining 56,875 eligible for vaccination, 50,682 have at least one-jab. That is 89% of all eligible residents.

    The Punch Line? If CIG requires the current 56,880 target of fully-vaccinated, that is OVER 100% of the 56,875 who are even eligible for vaccination.

    There is a REASON that vaccination has slowed to a crawl…

    • Conclusion: With a mean of 65,500 people and a 95% confidence interval setting an upper limit of 71,100 and a lower limit of 60,900… the bell-curve shape of that estimate confirms that there is only 47.5% confidence ( half of the 95%) the population is higher than 65,500 as is below 65,500.

      Also important is that at the limit of the curve… the figure of 71,000 used by CIG for vaccination….there is LESS THAN a 2.50% probability that the population is 71,000 or higher!…
      How does a Government use such a statistically meaningless figure as a target for vaccination? especially when 12.50% of them (the fictitious children portion that don’t exist) cannot even be vaccinated?

  4. As former Prime Minister Benjamin Disraeli once said: “There are three kinds of lies: lies, damned lies, and statistics.”

    No explanation is given as to why the ESO recommended that the government use the UPPER value, 70,686, to calculate vaccination ratios. They then “adjusted” that figure by adding another 420 residents.

    Had the government used the LOWER value of 60,886, even adding the “adjustment” of 420 residents, they would have come out to a total of 61,306. If you then multiply by 80%, you arrive at a goal of 49,044 residents to be vaccinated.

    Since, as reported above, there are 50,682 who have already received one jab, the 80% goal of FULL vaccination becomes attainable to achieve in a few weeks.

    Perhaps the government should take out its pencils and re-work those figures again.

  5. Well there’s quite a lot you could glean from those numbers but if you want a more accurate depiction of where you stand and more so why a chart/breakdown of the 3 groups – WP&GC – Caymanians – PR with just the number of 1 & 2 jabs and percentage of each would be most revealing.

    In light of these numbers I would say that without mandating vaccinations for WP&GC workers 80% is not achievable. On the surface it seems to me that that group receives the least benefit from being vaccinated. Just my 2 cents.