WORLD POPULATION IN 2050: ASSESSING THE PROJECTIONS
Bibliographic record
Abstract
This paper will review some population projections for the United States, the world, and selected major regions. The total population size, the youth dependency ratio, the elderly dependency ratio, and the total dependency ratio will receive most attention. The underlying assumptions regarding fertility, mortality, and migration will be reviewed. Projections from different sources will be compared where possible. But before looking to the future, I thought that it would be useful to have a glimpse into the past. Two thousand years ago, we had about a quarter of a billion people on the planet. It took sixteen to seventeen centuries to double to about one-half billion. The next doubling took less than two centuries, from the middle of the seventeenth century to around 1800. The next doubling took little over 100 years, and standing where we are now and looking back, the last doubling took about thirty-nine years. The second half of the twentieth century is the first time in all of human history in which the Earth’s population doubled within a single lifetime.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.009 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.004 | 0.004 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.002 | 0.005 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".