I write about applied economics, causal inference, pricing strategy, industrial organization, and marketplace economics. Most posts connect economic theory with real business decisions, drawing from my research and experience advising organizations on pricing, experimentation, and demand analysis.
Why Staggered DiD Can Fail Even When Parallel Trends Holds
July 2026 | Applied Economics | Causal Inference
A standard two-way fixed effects Difference-in-Differences estimator can produce biased
estimates under staggered treatment timing, even when parallel trends holds. This post
explains why, using the Goodman-Bacon decomposition, and how cohort-based estimators avoid
the problem.
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Why Parallel Trends Is the Most Important Assumption in Difference-in-Differences
July 2026 | Applied Economics | Causal Inference
A Difference-in-Differences estimate can look statistically clean and still be wrong. This post
explains why the parallel trends assumption is the foundation of every DiD analysis, what happens
when it fails, and how to test it using event study plots.
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How to Choose the Right Causal Inference Method
July 2026 | Applied Economics | Causal Inference | Industrial Organization
The hardest part of causal inference is not choosing a method. It is constructing
a credible counterfactual. When randomization is not possible, the challenge becomes
selecting the identification strategy whose assumptions are most credible for the setting.
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Why Platform Pricing Is Different: The Indirect Network Effect
July 2026 | Marketplace Economics | Industrial Organization
Most pricing frameworks are built for one group of customers. Platform businesses
require something different. A pricing decision on one side propagates through the
platform, changes behavior on the other side, and feeds back to affect the first side.
This is the indirect network effect, and why pricing structure often matters more than
price itself in platform markets.
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The CLV Paradox: Why High-Value Customers Are Not Always the Best Retention Targets
June 2026 | Marketplace Economics | Customer Lifetime Value
The customers generating the most lifetime revenue were not the best retention targets.
In this marketplace, the highest-spending segment returned least often, while lower-spending
customers generated the strongest retention opportunities. The result challenges a common
assumption behind many customer lifetime value programs.
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Seller Concentration and Marketplace Power: When More Sellers Does Not Mean More Competition
June 2026 | Marketplace Economics | Industrial Organization
96.3% of products in the marketplace I analyzed had exactly one seller. Among products
with multiple sellers, duopolies exhibit lower price dispersion than markets with three
or more sellers — a pattern consistent with tacit coordination at low seller counts and
greater pricing heterogeneity as competition increases. Seller count alone may not be a
reliable proxy for competitive intensity at the product level.
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Freight Is a Retention Lever: What Shipping Costs Reveal About Customer Behavior
June 2026 | Marketplace Economics | Industrial Organization
In the marketplace I analyzed, freight cost has a comparable effect on repeat purchase
probability as product price. The coefficients are -0.076 and -0.079 respectively.
Freight costs also vary by 50 to 80 percent across regions, driven by geographic distance
and distribution structure. Together, these results suggest that shipping policy is not
just a logistics decision — it shapes retention in a way that systematically disadvantages
high-freight regions.
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Platform Commission Misalignment: When Seller-Optimal Pricing and Platform Incentives Diverge
May 2026 | Marketplace Economics | Industrial Organization
Most marketplace platforms earn commission on gross merchandise value, not seller profit.
This creates a structural bias toward volume over margin. In the Electronics category I
analyzed, a 20% price increase is seller-optimal, improving profit by 5.6% while reducing
platform commission revenue by approximately 19%. The result highlights a structural
divergence between seller-optimal pricing and platform incentives — not only a pricing
problem, but an incentive design problem.
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The Lerner Index in Practice: When Elastic Demand Requires a Price Increase
May 2026 | Applied Economics | Pricing Strategy
The Lerner Index says elastic demand means lower markups. A revenue-maximizing algorithm
applied to an electronics category with elasticity of -2.18 recommends a 40% price cut,
projecting an 82.7% revenue increase. The Lerner rule recommends a 20% price increase.
Both are internally correct. They are optimizing different objective functions under the
same underlying demand structure. The key is what happens when you include the cost structure.
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When the Model Was Right and the Decision Was Wrong
May 2026 | Applied Economics | Pricing Strategy
In one electronics category, the revenue-optimal recommendation produced
an 82.7% increase in revenue and a 144% reduction in profit at the same time. The elasticity
estimate was correct. The optimization system was working as designed. The problem was the
objective function.
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When a Null Result Is the Answer: Aggregation Bias in Demand Estimation
May 2026 | Applied Economics | Econometrics
I estimated price elasticity at the bucket level and obtained a statistically insignificant
result. The model was not the problem. Aggregation masked the underlying demand signal
through composition effects within product buckets. Disaggregating back to the category
level recovered economically meaningful elasticities, illustrating a classic unit-of-analysis
problem first documented by Tellis (1988) that still appears in modern e-commerce marketplaces.
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What a 3% Repeat Purchase Rate Teaches About Marketplace Loyalty
May 2026 | Marketplace Economics
In the marketplace I analyzed, 97% of customers made exactly one purchase.
That looks like a loyalty problem. It is not. The repeat rate reflects the aggregator model,
not dissatisfaction. Among returning customers, 53% purchased from a different category within
29 days — a sequential pattern that looks like completing a room, not random browsing. The
implication for recommendation systems is direct.
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Why Cost Uncertainty Drives Direction in Pricing Optimization
April 2026 | Applied Economics | Pricing Strategy
Most pricing teams treat cost assumptions as background inputs and invest
heavily in demand modeling. My research suggests this sequence is backwards. A 5 percentage
point error in cost assumptions can reverse an optimal pricing recommendation entirely, while
a 20 percent elasticity error typically affects magnitude but not direction. The key distinction
is whether uncertainty crosses the breakeven cost threshold.
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The Revenue Maximization Trap: Why More Sales Can Mean Less Profit
April 2026 | Applied Economics | Pricing Strategy
A revenue-maximizing algorithm recommends a 40% price decrease for an
electronics category with elastic demand, projecting an 82.7% revenue increase. At a 65%
COGS structure, that recommendation reduces profit by 144%. The algorithm is technically
correct on its own terms and commercially destructive in practice. Here is why the
revenue-profit divergence happens and what to do about it.
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