Research Glossary

Key terms and definitions from applied economics research on food security, transit equity, education policy, and causal inference methods.

Food Security

Food Desert

A low-income census tract where at least 500 people or 33% of the population live more than 1 mile from a supermarket (urban) or 10 miles from a supermarket (rural), as defined by the USDA Economic Research Service.

The Food Desert Myth article reports zero food deserts by this federal definition and 4.7x variation in SNAP participation. That published comparison is under reconciliation and should not be treated as verified until its store, tract, and SNAP records match.

Mobility Desert

A neighborhood where grocery stores exist within 1 mile but transit access is inadequate (no stop within 0.5 miles or fewer than 2 stops nearby), making stores practically unreachable for residents without cars.

The Mobility Deserts article reports a 12% statewide rate and 1,086 neighborhoods. That population, its regional distribution, and the 150,000 to 250,000 resident estimate are under reconciliation because the public materials conflict over raw and unique transit-stop counts.

Vulnerability Paradox

A site-coined label for an article-reported hypothesis that tracts with closer stores can show higher SNAP participation or vulnerability proxies. It is not an established food-insecurity result.

The Food Access Vulnerability Paradox article reports lower mobility-desert rates for majority-minority tracts, while the Transit Equity and Race article reports the opposite direction for ostensibly similar inputs. Both results are under reconciliation. SNAP participation is a program-use measure, not a direct food-insecurity outcome.

SNAP Enrollment Gap

The difference between the number of people eligible for the Supplemental Nutrition Assistance Program and those actually enrolled, reflecting administrative barriers, stigma, or information gaps.

The Food Desert Myth article reports a 12% to 56% range across selected Santa Clara County tracts. The resulting 4.7x comparison is under reconciliation and should not be treated as verified until its source records match.

Extended Vulnerability Index

A proposed composite measure combining economic, geographic, mobility, and density factors at the census-tract level.

The article reports a 408-tract application, an association with SNAP participation, and sensitivity checks across alternative weights. Those values are not publicly reproduced. Because SNAP participation appears in the index and is also used as an evaluation outcome, the reported association is not an independent criterion-validity test.

Transit Equity

Distance-Transit Paradox

A site-coined label for an article-reported hypothesis that shorter grocery-store distance can coexist with weaker transit access. It is not a reconciled empirical result.

The Transit Equity and Race article reports higher mobility-desert rates for majority-minority tracts, while the Food Access Vulnerability Paradox article reports lower rates. The direction and population are under reconciliation.

Cal-ITP (California Integrated Travel Project)

A statewide GTFS data aggregation maintained by Caltrans and distributed through data.ca.gov. Feed coverage and deduplication still require project-level validation.

The site reports a 49% to 12% mobility-desert comparison using Cal-ITP data, but the article and pinned artifact conflict over raw and unique stop counts. The stop population and resulting rate are under reconciliation.

Related: Data Quality: 49% to 12%

Education Policy

Maintenance of Effort (MOE)

An IDEA Part B eligibility and compliance requirement that an LEA can meet under any one of four comparisons: local funds, State and local funds, local funds per capita, or State and local funds per capita. 34 C.F.R. § 300.203 defines those tests. Section 300.204 lists exceptions, and § 300.205 provides an adjustment in certain years.

A Too Early To Say article reports a 16.7% to 21.3% special-education budget-share change and proposes MOE as a mechanism. The article is not backed by a matching public output and does not show that general education absorbed all reductions.

Encroachment

In education finance, the practice of diverting general education funds to cover special education costs when special education expenses exceed designated special education revenue.

The displayed article-reported bins imply a weighted average of about 4.2%, while 7% of the displayed district distribution is in a category with a 13.2% mean. The table and district universe are not publicly reproduced.

Fiscal Cliff (Education)

A term for an abrupt budget decline when temporary funding ends.

A Too Early To Say article reports an 8.7% California K-12 funding decline during 2010-11, the final ARRA-funded year, as support was winding down. That aggregate comparison is article only, does not isolate ARRA funds, and has no matching public output.

Econometric Methods

Event Study

An econometric method that estimates the dynamic effect of a treatment or policy change by comparing outcomes at multiple time points before and after the intervention, testing for parallel pre-trends.

Event study designs allow researchers to visualize treatment effects over time and test whether treated and control groups were on similar trajectories before the policy change, a key assumption of causal inference.

Difference-in-Differences (DiD)

A quasi-experimental method that compares changes over time between a treatment group and a comparison group. A causal interpretation requires credible parallel trends and the other design assumptions; double differencing alone does not establish causality.

The COVID-era SNAP article previously reported a regression estimate that does not reconcile with its displayed group means. That estimate is withdrawn pending a saved model output. Overlapping ACS five-year vintages do not establish a causal COVID effect.

Synthetic Control Method

A statistical method that constructs a weighted combination of untreated units to serve as a counterfactual for a single treated unit, enabling causal inference when only one unit receives treatment.

Particularly useful in policy evaluation where a single jurisdiction implements a policy change and researchers need to estimate what would have happened without the intervention.

Research Glossary

Food Security

Transit Equity

Education Policy

Econometric Methods

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