Methods library · Eight research stages

Applied economics methods in the age of AI

This methods library is the practice layer behind Too Early To Say. It organizes how a real policy question becomes a defensible number through framing, data checks, identification, implementation, verification, interpretation, and evidence preservation.

AI is an instrument inside that practice. Agents handle search, first-pass implementation, reruns, and reconciliation. The economist retains the decisions that determine what the estimate means and whether the claim applies beyond the study setting.

Eight stages of the practice

The stages organize the current library by the research decision at stake. Each entry is one worked instance within the complete sequence.

Focused learning track

AI for Applied Researchers

The five-step guide applies the larger practice to an economist's first project with a coding agent. It stays a focused track inside the methods library.

  1. Literature review: pull benchmark numbers before code.
  2. Code generation: translate a methods paragraph into a checked pipeline.
  3. Data cleaning: classify noisy categories and report error.
  4. Quality assurance: try to falsify the result before reporting it.
  5. Documentation: trace every public number back to the analysis.

Full methods library

The complete archive contains 71 methodology articles. Selected studies include public code and documentation; availability varies by study.

Worked econometric and research-tool cases

Articles that examine a research decision from setup to failure check. Selected studies link to public code and documentation.

Matching in Python: a balanced covariate table doesn't make the estimate valid

A propensity-score match can pass every balance check and still return the wrong number. Observed-covariate balance does not establish that a comparable control existed.

Jul 2026
Applied Econometrics Reproducibility Causal Inference

Synthetic control in Python: read the pre-fit before the gap

A zero-error pre-treatment fit returns a clean gap of 6.1 against a planted effect of 6.0, and the same zero-error fit returns a wrong gap of 4.3 when no valid counterfactual exists. Pre-treatment fit quality determines whether the post-treatment gap is interpretable.

Jul 2026
applied-econometrics causal-inference python

Regression discontinuity in Python: getting the effect at the cutoff right

A global polynomial fit returns a clean, plausible 1.8 where the effect planted at the cutoff is 0.75. A local fit recovers about 0.75. The article explains regression discontinuity in Python and a confounder that the local fit does not adjust for.

Jul 2026
applied-econometrics causal-inference python

How to tell whether a double machine learning estimate is right

Double machine learning in Python: why a naive plug-in estimates 0.55 when the true effect is 1.0, how cross-fitting recovers 0.97, and the confounder it still cannot detect.

Jul 2026
applied-econometrics causal-inference python

Using difference-in-differences in practice

When difference-in-differences fits, which assumptions matter, and how the design assumptions fail, shown across worked cases with study-level material status. A decision table maps each situation to the estimator and the corresponding diagnostic requirement.

Jul 2026
applied-econometrics causal-inference difference-in-differences

Instrumental Variables in Python: Strength Is Not Validity

The Mroz walkthrough reports OLS at 0.1075 and IV at 0.0614. A first-stage F of 55.4 supports relevance only; it cannot establish the independence or exclusion arguments required for a causal interpretation.

Jul 2026
applied-econometrics causal-inference python

Rolling DiD with Few Units: Article-Reported Simulation

An instructional guide to transformation choice and small-sample inference. The simulation estimates and Python rebuild are article-reported and not publicly reproduced.

Jun 2026
ai-workflow applied-econometrics causal-inference

AI Econometrics: Using AI for Code, Not for Identification

A conceptual division of labor for AI-assisted econometrics. The exact outputs in its worked examples are article-reported and not publicly reproduced.

Jun 2026
ai-workflow applied-econometrics causal-inference

How do we know an AI's estimator does what we meant?

Rebuilding an estimator from a paper or package, the code can run without error and still be wrong. A routine that detects the mismatch: name the low-visibility choices in a spec, plant a known truth in a simulation, and read the code against its source.

Jun 2026
applied-econometrics reproducibility ai-workflow

Comparing logistic regression with language-model readouts for survey prediction

The article reports a local model comparison. Its scripts, data provenance, saved outputs, and run record are not public, so the exact rankings and metrics are not independently reproduced.

Jun 2026
ai-workflow applied-econometrics machine-learning

A regression view of steering vectors

The article reports a local estimator experiment. Its scripts, construction corpus, saved outputs, and run record are not public, so the numerical comparison is not independently reproduced.

Jun 2026
ai-workflow applied-econometrics machine-learning

Prediction-powered inference for AI-assisted survey estimation

The article teaches the estimator through a local HINTS imputation example and a separate simulation. Neither has a public script, data-provenance record, saved output, or run record.

Jun 2026
ai-workflow applied-econometrics machine-learning

Well-Executed but Not Important

The article classifies 2,493 published health-economics abstracts by contribution scope. Identification and Reframing labels are associated with fitted 1.91x and 2.26x differences on the citations-plus-one geometric scale relative to Calibration; the selected sample does not identify editorial importance or a causal effect.

May 2026
meta-research llm-classification citations

Cycling Through Bad Ideas Faster: An Article-Reported Medicaid Example

An iterative-critique workflow built around Medicaid branding estimates and elapsed-time comparisons that are not publicly reproduced.

May 2026
medicaid difference-in-differences ai-workflow

Claude Code Skills Get Stale. Audit Them Quarterly.

A repeatable audit for skills, hooks, and memory entries created for older models before they shape current analysis.

May 2026
tutorial claude-code

A pre-analysis plan for a coding agent

A three-layer architecture, rule, gate, and verification, for constraining reasoning-agent behavior when system prompts alone are not enough.

May 2026
tutorial agents

Building a Literature Surveillance System

Combining Google Scholar and Semantic Scholar sources with an AI assistant that integrates citation networks and detects reference errors.

April 2026
tutorial literature review

One Context File: A Workflow for Persistent Project Context

A teaching workflow for documenting project conventions in CLAUDE.md. Its session times, prevented-error counts, and savings estimates are not independently timed.

October 2025
tutorial claude-md

Methods-to-Code with AI: An Article-Reported Workflow

A precise methods paragraph serves as an implementation specification. The transit example and timing comparison are article-reported and not publicly reproduced.

October 2025
tutorial workflow

Cleaning a Research Codebase: An Article-Reported Example

A teaching workflow for mapping dependencies and reorganizing code. The script counts, changed imports, hashes, and timing claims are not publicly reproduced.

November 2025
tutorial refactoring

Robust API Collection: Pagination, Rate Limits, Failure Recovery

The collection safeguards are documented. The article-reported record total, cost, retry log, and zero-loss claim remain under reconciliation.

November 2025
tutorial api

Grocery Store Classifier Results Under Review

The article reports an iterative labeling result. Its full-population classification remains under reconciliation with the related policy pages.

October 2025
tutorial validation

The Retail Density Paradox: Why More Stores Mean Worse Data

Cross-validating SNAP retailer data against multiple authoritative sources documents provenance for each label.

October 2025
tutorial validation

Build Transit Travel-Time Matrices with Free Tools

Step-by-step guide to r5py, GTFS data, and multimodal accessibility analysis. The project-specific pair count is under reconciliation.

November 2025
tutorial r5py GTFS

Most recent

AI Econometrics: Using AI for Code, Not for Identification

A conceptual division of labor for AI-assisted econometrics. The exact outputs in its worked examples are article-reported and not publicly reproduced.

Jun 2026
ai-workflow applied-econometrics causal-inference

How do we know an AI's estimator does what we meant?

Rebuilding an estimator from a paper or package, the code can run without error and still be wrong. A routine that detects the mismatch: name the low-visibility choices in a spec, plant a known truth in a simulation, and read the code against its source.

Jun 2026
applied-econometrics reproducibility ai-workflow

Rolling DiD with Few Units: Article-Reported Simulation

An instructional guide to transformation choice and small-sample inference. The simulation estimates and Python rebuild are article-reported and not publicly reproduced.

Jun 2026
ai-workflow applied-econometrics causal-inference

Comparing logistic regression with language-model readouts for survey prediction

The article reports a local model comparison. Its scripts, data provenance, saved outputs, and run record are not public, so the exact rankings and metrics are not independently reproduced.

Jun 2026
ai-workflow applied-econometrics machine-learning

A regression view of steering vectors

The article reports a local estimator experiment. Its scripts, construction corpus, saved outputs, and run record are not public, so the numerical comparison is not independently reproduced.

Jun 2026
ai-workflow applied-econometrics machine-learning

Prediction-powered inference for AI-assisted survey estimation

The article teaches the estimator through a local HINTS imputation example and a separate simulation. Neither has a public script, data-provenance record, saved output, or run record.

Jun 2026
ai-workflow applied-econometrics machine-learning

Well-Executed but Not Important

The article classifies 2,493 published health-economics abstracts by contribution scope. Identification and Reframing labels are associated with fitted 1.91x and 2.26x differences on the citations-plus-one geometric scale relative to Calibration; the selected sample does not identify editorial importance or a causal effect.

May 2026
meta-research citations llm-classification

Cycling Through Bad Ideas Faster: An Article-Reported Medicaid Example

An iterative-critique workflow built around Medicaid branding estimates and elapsed-time comparisons that are not publicly reproduced.

May 2026
medicaid difference-in-differences ai-workflow

Claude Code Skills Get Stale. Audit Them Quarterly.

A proposed quarterly audit for skills, hooks, and memory entries created for older models, with hypothetical failure paths to turn into regression tests.

May 2026
claude-code research-workflow reproducibility

What AI Impact Looks Like in the Slow Data

Usage telemetry measures AI adoption; slow public data measures household conditions. The same AI tooling can process both at the cadence each source permits.

May 2026
ai-impact data-monitoring

A pre-analysis plan for a coding agent

A three-layer architecture for constraining reasoning-agent behavior: rule, gate, and verification. The proposed design combines architecture with explicit instructions.

May 2026
agents verification

Building a Literature Surveillance System

Google Scholar alerts and Semantic Scholar monitor academic literature. An AI coding assistant can combine sources, follow citation networks, and detect reference errors.

April 2026
literature review skills

Browse all 71 methodology articles by category below.

Medicaid program-integrity cases

What 238 Million Medicaid Billing Rows Can Support

Official HHS metadata confirms the row count. The article explains the file's screening uses and why its administrative fields do not supply a valid fraud label.

February 2026
T-MSIS data quality

The Label Problem: Why Fraud Labels Are Harder Than They Look

Exclusion lists are often used as fraud-label proxies, but their administrative definition differs from adjudicated fraud.

February 2026
LEIE labels

What Billing Patterns Actually Look Like

A guide to billing features, label contamination, and proxy bias. The provider comparisons remain article-reported and under reconciliation.

February 2026
billing analysis peer groups

Can a Classifier Find What Investigators Miss?

A guide to temporal validation and interpretable baselines. The model sample, base rate, and classifier metrics remain under reconciliation.

February 2026
machine learning SHAP

AI-assisted research

Well-Executed but Not Important

The article classifies 2,493 published health-economics abstracts by contribution scope. Identification and Reframing labels are associated with fitted 1.91x and 2.26x differences on the citations-plus-one geometric scale relative to Calibration; the selected sample does not identify editorial importance or a causal effect.

May 2026
meta-research llm-classification citations

Cycling Through Bad Ideas Faster: An Article-Reported Medicaid Example

An iterative-critique workflow built around Medicaid branding estimates and elapsed-time comparisons that are not publicly reproduced.

May 2026
medicaid difference-in-differences ai-workflow

One Context File: A Workflow for Persistent Project Context

A teaching workflow for documenting project conventions in CLAUDE.md. Its session times, prevented-error counts, and savings estimates are not independently timed.

October 2025

Methods-to-Code with AI: An Article-Reported Workflow

A precise methods paragraph serves as an implementation specification. The transit example and timing comparison are article-reported and not publicly reproduced.

October 2025

Cleaning a Research Codebase: An Article-Reported Example

A teaching workflow for mapping dependencies and reorganizing code. The script counts, changed imports, hashes, and timing claims are not publicly reproduced.

November 2025

Data collection and validation

Robust API Collection: Pagination, Rate Limits, Failure Recovery

The collection safeguards are documented. The article-reported record total, cost, retry log, and zero-loss claim remain under reconciliation.

November 2025

Grocery Store Classifier Results Under Review

The article reports an iterative labeling result. Its full-population classification remains under reconciliation with the related policy pages.

October 2025

The Retail Density Paradox: Why More Stores Mean Worse Data

Cross-validating SNAP retailer data against multiple authoritative sources.

October 2025

Spatial analysis

Build Transit Travel-Time Matrices with Free Tools

Step-by-step guide to r5py, GTFS data, and multimodal accessibility analysis. The project-specific pair count is under reconciliation.

November 2025
tutorial r5py GTFS

Residualized Accessibility Index: An Article-Reported Case

A regression-residual lesson built around article-reported coefficients and ranks that are not publicly reproduced.

November 2025

All remaining methodology articles

The rest of the library: the full set of AI-assisted research workflows, code tutorials, and method walkthroughs.

AI Research Workflows

Claude Code guides for academic research: CLAUDE.md context files, skills, hooks, MCP servers, context window management, and verification practices. From first session to personal AI infrastructure.

February 2026

Building Our Research System: Putting It All Together

How CLAUDE.md, skills, hooks, and MCP servers combine into a personal research system. Part 5 of the Advanced Tier series.

January 2026

Claude Code Guide

A 14-article guide to Claude Code: context management, session workflows, agent spawning, and personal AI infrastructure. Estimated 2-3 hours total reading time.

A First Session with Claude Code

A practical walkthrough of what Claude Code can and cannot do, with prompting patterns and a complete first-task example.

February 2026

A Starter Kit for the Economist's First Week in Claude Code

A starter kit for economists using Claude Code: one CLAUDE.md template, a verification checklist, three starter skills, and a week-one glossary.

July 2026

The Cold Start Problem

How CLAUDE.md supplies project context at the start of an AI session.

December 2025

Why It Forgot Everything: Understanding Context

Understanding how AI context windows work, why sessions reset, and how to work with this fundamental limitation of large language models.

February 2026

Context Window Budgeting

Treating tokens as a finite resource, and knowing when to spawn agents versus work directly.

January 2026

Reading Our Analysis Files

How Claude Code explores research projects using three core tools: Read (look at a file), Glob (find files by pattern), and Grep (search inside files).

February 2026

Research Phases Need Different Prompts

Exploration, implementation, and documentation require different AI prompting strategies. Match the prompt to the phase.

January 2026

Creating Skills: Reusable Workflows for Research

Skills store reusable task instructions that Claude Code can apply when the task matches their trigger.

January 2026

Hooks: Automation Without Asking

Hooks are automatic triggers that run without asking - like auto-save, but for research tasks. A power-user feature, entirely optional.

March 2026

Connecting Claude to Outside Services: FRED, Census, and Beyond

How to connect Claude Code to external data sources like FRED, Census, and Google Scholar for querying those sources through Claude Code.

March 2026

Creating Helpers: When to Delegate Work

When to create separate Claude Code helpers for focused work, how to design tasks that are easy to hand off, and patterns for running multiple helpers at the same time.

January 2026

What Agents Actually Do (And What They Don’t)

A conceptual account of how task specification and project context can bound agent behavior. No controlled comparison here isolates those factors from model capability.

March 2026

What We Mistake for AI Capability

A hypothesis that task tolerance and specification shape perceived AI capability, plus the controlled comparison needed to separate those factors from the model.

March 2026

The Verification Tax

Verification checks detect unsupported claims before later steps reuse them.

January 2026

Copy-Paste vs. Agent Coding: An Illustrative Comparison

A teaching comparison of chat-based and repository-aware workflows. The cycle count and error story are illustrative scenarios, not measured benchmarks.

October 2025

End-of-Session Hygiene: What to Capture Before Context Resets

A capture routine for handing decisions, open questions, and verification state to the next session.

January 2026

Reading Claude Code usage data

A Claude Code /insights report supports different lessons at beginner and intermediate levels from the same underlying data.

February 2026

Running Claude Code skills, for applied economists

A setup guide for the public TETS skill skeletons. Some workflows require user-supplied inputs and do not ship with a turnkey example run.

May 2026

Why Claude and ChatGPT Struggle with Research Graphics (And What Makes Antigravity Prompts Work)

Structured prompts make layout and verification constraints explicit. The article's numerical figure examples are hypothetical teaching inputs.

December 2025

Staging LinkedIn Posts with Browser Automation

A case study in form-filling workflows that keep humans in the loop. Browser automation handles navigation and data entry while the human retains final approval.

February 2026

The Data We Forgot We Had: A Tagging System for Research Serendipity

Tag datasets by the questions they can answer, not just what they contain. A question-first system makes existing datasets searchable by research question.

January 2026

Open-Source Methods

Python tutorials for applied economics: difference-in-differences, spatial joins, SHAP interpretation, GTFS validation, Census API pipelines, and imbalanced classification.

February 2026

Difference-in-Differences in Python: When TWFE Misleads

A statsmodels workflow for event study estimation, with the diagnostics that separate credible estimates from noise.

February 2026

Imbalanced Classification: An Article-Reported Example

An instructional workflow for class imbalance and rare-class metrics. Dataset counts, model results, and the named implementation are not publicly reproduced.

February 2026

SHAP Classifier Interpretation: An Article-Reported Example

An instructional SHAP workflow. The model metrics, importance shares, runtime, and named implementation are not publicly reproduced.

February 2026

How to Build a Census Data Pipeline

A Python workflow for pulling ACS data from the Census API, including the validation checks that prevent bad data from reaching the analysis.

February 2026

GTFS Validation in Python: An Article-Reported Workflow

Six instructional validation layers. The named project inputs, failure counts, and implementation are not publicly reproduced.

February 2026

A reference library for empirical methods

A Claude Code skill that generates a structured papers.md block from a DOI or PDF, documenting the estimator, identification strategy, and named assumptions, with a misattribution flag when the bibliography credits…

May 2026

A common shape for econ replication packages

A public code skeleton for measuring package structure. Seed files, tests, validation outputs, and a public panel are not included, so it is not a turnkey run.

May 2026

A field map for causal-inference methods

A Claude Code skill that builds a navigable citation network around a single method family, recording the seminal references, the current authors, the recent applications, and papers that…

May 2026

Monitoring Government Data Portals

A case study in tracking California health data releases with Claude Code. Detect new data releases without manual checking across HCAI, DHCS, DOF, and other state agencies.

February 2026

A Proxy Method for Classifying Grocery Stores at Scale

An article-reported proxy classification. The source data, classification tables, code, and matched outputs are not public.

GeoPandas Spatial Joins: An Illustrative Workflow

An illustrative workflow from point-to-polygon joins to local cluster diagnostics. The empirical values and named implementation are not publicly reproduced.

February 2026

Crime Geography Precision: An Article-Reported Case

The article reports a 22-fold crime range. No matching public script, run record, or saved output currently reproduces the geographic case.

December 2025

County Rankings and Policy Context: An Article-Reported Case

The article reports a 2.3-fold county comparison. No matching public script, run record, or saved output currently reproduces the rankings.

November 2025

Scaling Statewide: An Article-Reported Case

The pilot and statewide counts, timings, classifications, and findings are article-reported. The original repository no longer resolves.

December 2025

Parallel-Trends Sensitivity: An Article-Reported Case

A sensitivity-analysis lesson built around bank-closure estimates and diagnostics that are not publicly reproduced.

December 2025

When the parallel-trends test fails on one lead, what's left?

An article-reported TWFE-DiD exercise on SNAP BBCE adoption. The panel, estimates, and diagnostics are not publicly reproduced.

May 2026

Frequently asked questions

What is AI-assisted research?

AI-assisted research places a coding agent inside a researcher-defined workflow. The researcher supplies the estimand, variable definitions, data constraints, and acceptance checks. The agent assists with search, implementation, reruns, and documentation. The researcher verifies the output before making the reporting decision. The context-file article shows one instructional setup and labels its savings estimates as independently unmeasured.

How can transit accessibility be calculated with open-source tools?

r5py provides a Python interface to Conveyal's R5 routing engine. Combined with public GTFS feeds, it can build multimodal travel-time matrices without a proprietary software license. Data preparation and computing resources still require a documented workflow. The r5py tutorial explains the method and labels its project-specific pair count under reconciliation.

How is data quality validated?

The grocery-store classifier article reports 94% accuracy from an iterative labeling exercise. Its full-population classification remains under reconciliation with the related policy pages, so the validation result and population result have separate evidence statuses.

Which studies have replication materials?

Selected studies include public code and documentation. Availability varies by study and source license. The main analysis repository holds the materials currently available.