It is clear that the CPPI can now be used to review port performance over time. To be fair, previous versions of the report did not enable a robust time-based analysis because those earlier versions were focused on comparing port performance within that year.
In the most recent report, the earlier data was “normalized”. That’s the statistical way of saying that different values of different things being judged on different scales were adjusted so they could be measured and judged on a common scale that year. The earlier CPPIs highlighted comparability between different ports in the same year.
Previously, when working out both the administrative and statistical approach, the World Bank took the average score of all ports that year and set that as zero. There were additional year-specific factors in the statistical approach too.
This year though, it’s different. As the World Bank says, the “only way to make valid [comparisons over time] would be to work with the operational data”. And so that’s exactly what they did.
An explanation
The World Bank explains it well, so we’ll let them speak for themselves:
“For this year’s report, we applied a single reference distribution based on 2024 data and used it as the basis for mean centering all years’ data. Using the raw operational variables, we compute the mean for each ship size group and each relevant variable based on the 2024 dataset. We then recalculate… scores for previous years using these 2024-based parameters… … to maintain consistency in ship size groups and port inclusion criteria, we apply the 2024 group definitions retrospectively to earlier years. This ensures that changes in composition do not affect comparability… … this enables us to calculate changes over time… Adopting this rebasing approach allows for time series analysis, trend lines, and policy-relevant performance tracking,” the World Bank says. If you don’t believe us, feel free to look it up. It’s on pages 52 and 53, under the heading “5.5 Trends: Comparing Five Years of CPPIs”.
Look, this is not the easiest thing to understand. It certainly took us a few goes to get it.
Saying it simply
Let us put in simple, nonstatistical, language for you:
• Using operational data, the World Bank worked out a centre point in the 2024 data (technically they worked out the mean of the 2024 reference distribution. Us lesser mortals can assume “centre point” covers it adequately).
• They recalculated all scores for all years with reference to that point.
• That data selection and subsequent re-calculation means:
• port performance can now be tracked over time
• policymakers can have port performance tracked for policy purposes
• we can now see, over time, whether port performance is improving or declining
So, we wouldn’t normally say what we’re about to say. But, in this particular case, we have to.
Commentary which claims that the CPPI can’t be used to call out port performance over time is not merely an example of someone having a difference of opinion, nor is it just a different way of thinking about it. That kind of commentary is no longer valid.
It is just wrong.
Flat. Out. Wrong.
Disregard.
