Data is compiled from programme videos or transcripts and then standardised into a structured database.
The key principle is consistency rather than pretending the programme is more precise than it really is.
How expert statistics are compiled
Expert statistics describe results for teams supervised by the expert across indexed episodes, rather than attributing every purchase to the expert personally. Episode types and currencies are kept separate; no currency conversion is applied. A complete monetary total is unavailable when one or more contributing team totals cannot be calculated.
Hammer returns use items with both purchase and hammer prices recorded in the same currency. ROI is total profit divided by total purchase cost for that matched sample, expressed as a percentage, rather than an average of individual item percentages. Missing values are not zero; a zero total cost does not produce a calculable ROI.
Typical results and consistency
Median profit is the middle result when calculable profits are ordered, or the mean of the two middle results for an even sample. Lower and upper quartiles mark the middle half of results and are shown for at least four calculable items. They use linear interpolation at positions (n − 1) × 0.25 and (n − 1) × 0.75 in a zero-based ordered sample. Loss rate is the percentage of calculable items with a negative hammer profit. Sample sizes are shown alongside the results; small samples should be interpreted cautiously.
Buying profiles, series and price bands
Buying profiles describe category, primary material and period. Shares use all items in the selected scope as the denominator, including unclassified items, so recorded classifications may total less than 100%. Classification coverage is shown separately. Ties for the most-purchased classification are retained.
Series rows cover indexed appearances, ordered by series number, rather than a complete career chronology. Purchase-price bands are 0 to under 25, 25 to under 50, 50 to under 100, 100 to under 200, and 200 or more, in the relevant purchase currency. Each lower limit is included and each upper limit excluded. Items without a purchase price cannot enter a price band.
Core purchases and bonus items
“Calculable Competition Items” counts selected items whose competition contribution can be calculated. “Calculable Hammer Items” counts items with a recorded purchase price and hammer price in the same currency, regardless of whether the item was selected for the competition. Category Breakdown uses hammer results. Competition and hammer figures can differ for protected values, stolen items, disqualifications and rejected bonuses; an unknown hammer price is not treated as zero.
Most-Purchased Category is determined by the number of items bought. Best-Selling Category is determined by total recorded hammer receipts, not competition returns or profit. Total Hammer Return includes every recorded hammer price; Hammer ROI uses only the matched sample with both prices recorded in the same currency. As a result, total hammer return and total spending need not reproduce the displayed ROI when their available samples differ.
Core and bonus rows describe items from the expert’s supervised teams, regardless of who bought the bonus. Hammer results include rejected bonuses where calculable; competition profit includes only selected items with calculable contributions. Unknown item roles remain separate.
Category performance against the archive
Category comparisons require at least ten calculable items in both samples. The archive benchmark includes the expert’s own teams and matches episode type, competition currency, purchase currency and hammer currency. The difference is the team average hammer profit minus the archive average. This is a descriptive comparison, not a ranking or a measure of the expert’s individual influence.
How episodes and series are recorded
Ideally, I would list episodes and series as they appear on the BBC's Bargain Hunt page.
The Beeb, with its rather arbitrary approach to its own indexing, has other ideas.
Take Series 27.
At the time of writing, the series page lists 32 episodes, each with a sub-heading marking it as the xth episode of 32.
All seems in order.
But look closer.
Not only are episodes 9 and 31 missing from the list, two episodes are labelled as episode 15, and another two as episode 18.
That isn't a numbering error.
The BBC's Genome Project, compiled from the Radio Times listings, shows that, yes, two episodes were listed as the fifteenth of the series, and two as the eighteenth.
What's more, the listings also show gaps in the schedule where episodes 9 and 31 should be.
The numbers don't add up.
The BBC says Series 27 contained 32 episodes.
The schedule suggests 34.
What, then, is The Gavel Index to do?
Implement its own logic is what.
Series align with the BBC designation – but episodes are ordered by their broadcast date.
The first episode broadcast in the series is episode 1, the second is episode 2, and so on.
What the BBC says becomes irrelevant.
This occasionally produces episode counts which differ from the BBC's own numbering.
Some series gain episodes.
Some series lose episodes.
That is a problem for Aunty to solve.
How item categories and types are defined
Assigning a type is the easier of the two: it is simply what an item is.
A lamp is a lamp.
A chair is a chair.
A spoon is a spoon.
Classifying a category is more difficult for some items than others.
A lamp falling under the Lighting category is easy enough.
So too is categorising a chair as a piece of furniture.
Harder is what to do with the spoon.
After much thought, I decided to arrange items into the categories where most of the item's value lies.
A stainless steel serving spoon, therefore, falls under the Kitchen & Domestic category, whereas a silver serving spoon is listed within the Silver & Metalware category.
This is not a perfect system, but it is a consistent one.
Period, primary material and additional material provide further classifications where that information is recorded.
How item categories and types are named
Item categories and types are standardised to keep the database usable. That means very similar objects may be
grouped under a common type for analysis. The full wording and nuance of the object is in the item description.
How the database treats missing or unstated information
Sometimes Bargain Hunt does not state a figure or fact: an item might not receive an estimate or it may not be fully described.
In situations where the show does not provide information, the database does not invent it; it leaves the relevant field blank.
Not all blank values mean the information is impossible to find elsewhere, mind;
they can also mean the information is not currently confirmed for the purposes of this dataset.