Curriculum·R405 Strategy Development and Validation·about 34 min
The journal as a data pipeline
By the end of this lesson you can
- →Specify the journal as a schema rather than as a diary, and name the required fields
- →Explain why every aggregate must be re-derivable from the raw rows
- →Compute how a silently truncated range changes a reported expectancy
- →Set the review cadence and state what each review is allowed to change
Senior · enrolled learners
This lesson opens with Growth in a Time of Debt, and its replication, 2010 to 2013.
- What happened
- Carmen Reinhart and Kenneth Rogoff published Growth in a Time of Debt in 2010, reporting that average real growth collapses to negative 0.1 percent once public debt exceeds 90 percent of GDP. The finding was widely cited in policy debate. In 2013 Thomas Herndon, Michael Ash and Robert Pollin at the University of Massachusetts Amherst were unable to reproduce it and obtained the underlying spreadsheet. They identified three separate problems: a coding error in which an averaging formula was not extended far enough down the column and therefore excluded five countries, an unconventional weighting scheme, and selective exclusions of available data. Correcting them, the average real growth rate for countries above the 90 percent threshold was 2.2 percent rather than negative 0.1 percent.
- The decision point
- The error was not subtle mathematics, it was a range that did not reach the bottom of the data, and it survived publication and years of citation because nobody could re-run the calculation. What made the correction possible was not expertise, it was access to the file. An aggregate that cannot be re-derived from its raw inputs is not a finding, it is a claim, and the distinction only becomes visible when somebody tries.
What you will be able to answer
- →What is the journal?
- →Which fields are required?
- →What does a truncated range cost?
- →What is a review allowed to change?
Orientation and Year One are open: anyone can read them without an account. From Year Two onward the lessons are for enrolled learners, because progress through the later years only means anything if it is tracked against a record.
It is free. We do not sell the list and there is nothing to buy at the end of it.
Sources and review
- https://peri.umass.edu/publication/does-high-public-debt-consistently-stifle-economic-growth-a-critique-of-reinhart-and-rogoff/
- https://retractionwatch.com/2013/04/18/influential-reinhart-rogoff-economics-paper-suffers-database-error/
- https://theconversation.com/the-reinhart-rogoff-error-or-how-not-to-excel-at-economics-13646
- https://www.weforum.org/stories/2013/04/a-brief-guide-to-the-reinhart-rogoff-discussion/
Confidence high·Volatility low·Reviewed 2026-08-07·Owner unassigned
Contested
The economic significance of the correction was disputed at length, with the original authors accepting the coding error while defending other elements of the analysis and the broader association between high debt and lower growth. This lesson uses the case for its reproducibility lesson only and takes no position on the underlying economics.
S211-05 owns the reporting stack as a Sophomore-level practice, covering how to capture and store trade data. This lesson owns the journal as the input to validation specifically, being the schema that makes expectancy, intervals and review possible. Keep the split.
R411-06 covers reviewing automated performance, where the journal is produced by the system rather than by hand. The schema is the same and the failure modes differ. Keep that split too.