Methodology

How BasketWatch tracks Irish grocery prices

Every figure on this site comes from our own daily measurement of real shelf prices. Here is exactly what we collect, how often, and how we keep the numbers honest.

Coverage

We track around 45,000 grocery products across Aldi, Tesco, SuperValu and Dunnes Stores. For each product we capture its shelf price, its unit price (per litre or kilogram), any promotion, any loyalty price, and its category, every day.

How often

The full catalogue and prices are collected nightly, building a day-by-day historical record rather than a one-off snapshot. The Price Pulse report is published weekly.

Three signals, kept separate

A grocery price moves for three different reasons, and we never blend them into one number:

• Shelf ticket. The standing price on the shelf. When we report inflation, this is what we mean.
• Promotions. Temporary price reductions. We report shelf-price change on the ticket excluding promotions, so a promotion ending is never counted as a price rise.
• Loyalty. Member pricing such as Tesco Clubcard and SuperValu Real Rewards, reported separately from the shelf price.

Comparing across stores

Cross-store comparisons are like-for-like on matched pack sizes and product variants. Where we name a cheapest or best-value option, we rank by price per litre or kilogram, not the lowest absolute price, so a larger pack that is cheaper per unit is not flattered by a higher ticket.

Data quality

Automated daily checks, a morning re-verification pass, and independent live page sweeps catch and correct the known quirks of each retailer's data (for example a loyalty price occasionally being served in place of the shelf price). A figure that looks wrong the morning after a promotion changes is usually a retailer timing artefact that corrects itself within hours, not a lasting error.

Limitations, in the interest of honesty

• Headline savings are list savings, not a promise: you only bank them on items you would have bought anyway.
• Shelf prices drift over time, which is exactly why we track them daily rather than quoting a single snapshot.
• Some retailers do not expose every field (barcodes, for instance), so cross-store matching relies on product names and attributes.

Independence and use of data

BasketWatch is not affiliated with, endorsed by, or sponsored by any retailer. Data is collected from publicly available sources for lawful market research. Questions and corrections are welcome at info@basketwatchireland.com.