Benchmark Methodology

1. Data collection

All price data on SupplyIndex comes from independent UK practices: what they actually paid, either typed in by the practice or read from an invoice they upload. We do not scrape supplier websites, accept price list submissions from suppliers, or use list prices as data points.

The supplier directory spans every sector — dental, optical, veterinary, pharmacy, aesthetics, audiology and allied health. Benchmarks are in build: each one unlocks only once it clears the thresholds below, starting with aesthetics and dental. Cross-sector overheads (card processing, energy, telephony, insurance and more) are available to every practice from day one.

Practices submit data via four methods:

2. Validation pipeline

Invoices and typed-in prices are checked in different ways. Invoices run through the checks below; typed-in prices are weighted by who sent them and filtered for outliers (see section 3).

3. Benchmark calculation

Benchmarks are recomputed every day from prices paid in the last 12 months. Before any percentile is taken:

• Each price is weighted by its source. Confirmed invoice lines and prices from a confirmed practice email count in full; prices from a confirmed personal email (Gmail, Outlook and similar) count half; prices from an email that was never confirmed count a quarter. Temporary and throwaway email addresses are ignored.
• Outliers are removed. A price more than three times above or below the typical price for that product, or far outside the spread of the rest, is dropped — these are almost always typos or a pack price entered as a unit price. We also audit a sample of contributions — asking the practice for the invoice or order confirmation — and exclude anything that can’t be backed up.
• No practice can dominate. However many prices one practice enters for a product, together they carry at most the weight of three.

For each product with enough data we then report weighted percentiles:

Minimum data threshold: We require prices from at least 5 distinct practices before publishing a benchmark for a product. Below this threshold, products show a “Benchmark pending” status. This prevents small datasets from producing misleading benchmarks.

4. Freshness and trends

Benchmarks are recomputed every day, so they always reflect the latest prices practices have given us. Weighting follows the fixed rules in section 3 — we never adjust an individual figure by hand, though we do exclude ones that are clearly wrong.

We keep a monthly history for each unlocked product so you can see how a price has moved over time, and we alert members tracking a product when its median moves materially (5% or more) between runs.

5. Anonymisation and privacy

Individual practice prices are never disclosed. All benchmarks are aggregated statistics only. Additionally:

• Individual practice prices are never shown — every benchmark is an aggregate across at least 5 distinct practices
• A benchmark is only published once it clears the minimum threshold (prices from at least 5 different practices); below that it shows as “benchmark pending”
• NHS pricing is held separately and excluded from private benchmarks by default
• You can request deletion of your contributed data at any time

6. How we select panel suppliers

The supplier directory and our negotiated member offers are different. Directory entries are factual listings; appearing there does not mean that SupplyIndex has selected or endorsed a supplier. A panel supplier is a provider with whom we have agreed a member offer.

Price matters, but it is not our only test. A low rate can be poor value if missed collections, downtime, weak support, billing errors or a difficult handover create larger costs inside the practice. Poor service can cost more than money: it can cost staff time, patient trust, compliance confidence and continuity of care.

When developing a member offer, we consider:

• the price and the full contract terms, including renewal and exit conditions;
• service reliability, implementation and operational fit for independent practices;
• support responsiveness, escalation routes and accountability when something goes wrong;
• relevant compliance, security and data-protection requirements; and
• whether the proposition can work clearly and consistently across our member base.

We do not rank suppliers or claim that one provider suits every practice. Members contract directly with the supplier and make their own decision. Our role is to negotiate from combined demand and build offers in which price and service are both taken seriously. Read more in The cheapest supplier can cost the most.

7. Limitations

We are committed to honest communication about what our benchmarks can and cannot tell you: