Barcode Betty
52e89ec236
Critical fixes: - stores.md: Correct supported retailers to Meijer, Kroger, Target. Remove Safeway (never scoped). Replace named Coming Soon list with generic demand-based evaluation language. - privacy.md: Replace all OAuth/API claims with accurate language describing read-only headless browser access to loyalty portals. - about.md: Remove "price gouging on our roadmap" claim. Clarify USDA FoodData Central is reference data only, not a source of price data. - blog/price-gouging-vs-shrinkflation.md: Remove roadmap claim. Remove implication that price gouging detection is coming. - methodology.md: Fix cereal example math — 16.2% → 16.1%. Use raw values per the stated formula. Clarify USDA FoodData Central role for package sizing baselines only. - how-it-works.md: Correct retailers. Remove "(yet)" from receipt claim. Clarify USDA FoodData Central is reference data. Important fixes: - press-kit.md: Correct supported stores. Remove USDA FoodData Central from dollar-cost attribution — reattribute to CartSnitch analysis of manufacturer packaging data. - app-store-listing.md: Remove "thousands of products" claims (pre-launch beta, quantity unverified). - social/launch-day-posts.md: Remove "thousands of products" claim. Correct retailer list. Co-Authored-By: Paperclip <noreply@paperclip.ing>
103 lines
3.8 KiB
Markdown
103 lines
3.8 KiB
Markdown
# How We Calculate Shrinkflation: Our Methodology
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We believe consumers deserve to verify our work. Here's exactly how we calculate shrinkflation percentages and where our data comes from.
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---
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## The Core Formula
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For every product we track, we calculate:
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**Unit Price = Shelf Price ÷ Package Size**
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Then we calculate the shrinkflation percentage:
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**Shrinkflation % = (New Unit Price ÷ Old Unit Price) − 1**
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This gives us the effective price increase — accounting for both size changes and price changes.
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**Example:**
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- 2021: Cereal at $4.99 for 18 oz → Unit price: $4.99 ÷ 18 oz = $0.277/oz
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- 2024: Same cereal at $4.99 for 15.5 oz → Unit price: $4.99 ÷ 15.5 oz = $0.322/oz
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Shrinkflation % = ($4.99 ÷ 15.5) ÷ ($4.99 ÷ 18) − 1 = 16.1%
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The shelf price is the same. The unit price went up 16.1%.
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---
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## Data Sources
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We use multiple data sources to build our shrinkflation rankings:
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### 1. Manufacturer Packaging Data
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We track documented changes in product sizes as reported by manufacturers. This includes:
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- Net weight changes on packaging
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- Count-per-package changes (e.g., 4 rolls → 3 rolls)
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- Volume changes in liquid products
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### 2. USDA FoodData Central
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The USDA FoodData Central database provides reference data on product sizes and nutrition, which we use as baselines for historical comparison.
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**URL:** https://fdc.nal.usda.gov/
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### 3. Public Retail Data
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When available, we cross-reference shelf prices from public retailer sources to validate price continuity.
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---
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## How We Rank Shrinkflation Offenders
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Our top shrinkflation offenders rankings are based on the calculated shrinkflation percentage for each product. We rank products by:
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1. **Highest shrinkflation percentage** — the largest effective unit price increase
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2. **Across consistent time periods** — comparing current sizes/prices to documented baselines from 2020–2024
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3. **By product category** — cereals, snacks, dairy, household goods, etc.
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We only include products where we have documented evidence of a size or price change. We do not estimate shrinkflation for products we cannot verify.
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---
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## Shrinkflation vs Regular Price Increases
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We distinguish between:
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- **Shrinkflation** — Package size decreases while shelf price stays the same or increases. Unit price goes up.
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- **Regular price increase** — Package size stays the same, shelf price goes up. Unit price goes up.
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- **Combined shrinkflation + price increase** — Package size decreases AND shelf price increases. Unit price goes up significantly.
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All three result in a higher unit price. Our percentages capture the total effective increase.
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---
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## What We Don't Do
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- We don't estimate shrinkflation without documented evidence
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- We don't include products we cannot verify
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- We don't adjust our calculations based on brand or retailer pressure
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- We don't publish specific rankings until we can verify the underlying data
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---
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## Production Data vs Estimates
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**Before launch (current):** Our shrinkflation percentages are based on publicly available manufacturer packaging data. USDA FoodData Central provides reference data for package sizing baselines. These are directional estimates — they tell you the pattern is real.
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**After production deployment:** Once we have a live product with real transaction data, we'll be able to run the numbers against actual purchase data. This will validate and refine our estimates.
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We will always note when statistics are directional estimates versus based on production data.
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---
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## Future: Publishing Our Queries
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Once production is live, we plan to publish the SQL queries behind our shrinkflation calculations — so anyone can run them against our data and verify our work.
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This is part of our commitment to transparency.
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---
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## Questions?
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If you have questions about our methodology or believe we've made an error, email us: hello@cartsnitch.app
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