Is it Necessary to Relax the IID Assumptions in the Logsum-Based Accessibility Analysis?
Bibliographic record
Abstract
Accessibility is an important link between transportation and land use. As a typical measure of accessibility, logsum or a utility-based measure has been widely used in project appraisal, urban transit accessibility evaluation, destination choice, and network vulnerability analysis. Since the logsum term is the log of the denominator of the choice probability expression, it inherits the independently and identically distributed (IID) assumptions of the classical multinomial logit (MNL) route choice model. This paper aims to explore whether the IID assumptions have a significant effect on the logsum-based accessibility analysis, given that accessibility analysis focuses at the origin-destination (O-D) level and zonal level (aggregate analysis) rather than at the route level (disaggregate analysis). We derive two new logsum terms for two representative extended logit stochastic user equilibrium (SUE) models, that is, the C-logit model for relaxing the independence assumption and the MNL model with scaling effect (MNLs) for relaxing the identically distributed assumption. The case analysis of a real network in Winnipeg, Canada shows that: (1) there does exist a difference in accessibility evaluation among the three logsum terms using the three route choice models; (2) relaxing the identically distributed assumption is more important than the independence assumption since the difference in accessibility evaluation between MNLs-logsum and MNL-logsum is larger than that between C-logit-logsum and MNL-logsum; (3) the difference in accessibility evaluation at the zonal level is smaller than that at the O-D level; and (4) the difference increases with the dispersion parameter.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.026 | 0.124 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.003 | 0.010 |
| Open science | 0.005 | 0.004 |
| Research integrity | 0.002 | 0.007 |
| Insufficient payload (model declined to judge) | 0.005 | 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".