Are Returns to Scale with Variable Network Size Adequate for Transport Industry Structure Analysis?
Bibliographic record
Abstract
It is customary to analyze transport industry structure using two indices: (1) economies of density and (2) economies of scale with variable network size. The latter has been defined to analyze the behavior of costs when output and network size expand simultaneously. After reviewing in detail what is intended with the calculation of RTS under this definition, we show analytically that, when the spatial aspects underlying transport production are taken into account, the seemingly reasonable conditions imposed on the aggregate output descriptions and the network variable conceal implicit output expansions that are not uniquely defined: they happen to depend on the specification of variables and on the evaluation point. Furthermore, most of the multiple output expansions analyzed correspond to cases that are hardly instructive. We conclude that this index is inherently ambiguous, hardly contributes to an adequate analysis of transport industry structure, and should be replaced by the calculation of economies of spatial scope (Journal of Economic Literature L91, L11, D40).
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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 | 0.006 | 0.040 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.002 | 0.013 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".