| Compare printed weekly subtotals with parish-summed mortality counts · Published: September 22, 2026
Arithmetic Accuracy
Printed weekly bills reported subtotals for groups of London parishes. This explorer compares those printed subtotals with totals calculated from the individual parish entries, using the current Death by Numbers database rather than a fixed snapshot, so it reflects corrections and new transcriptions as they are added.
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Arithmetic differences by year and week
Color intensity represents the logarithmic difference, allowing small and unusually large discrepancies to remain visible together. The outlined column is the selected detail year. Click any column to select it.
Weekly differences
View the selected year as a table
| Week | Printed subtotal | Parish sum | Difference | Legible | Mixed copies More than one copy of this week's bill survives, and its figures come from different copies (the largest readable value for each parish and subtotal). A difference here may reflect disagreement between copies rather than an error on one printed bill. |
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How these figures are calculated
An arithmetic difference is the printed subtotal minus the sum of the individual parish counts. Positive values mean the printed subtotal is larger; negative values mean the parish sum is larger. Only weekly bills are included, and the Westminster pesthouse is left out of the parish sums because the printed subtotals do not include it. A week counts as legible only when none of its parish counts or subtotals is marked illegible.
Some weeks survive in more than one copy, and the copies do not always agree. Where that happens the database keeps the largest readable value for each parish and each subtotal, so a week’s figures can come from different copies. Those weeks are marked as mixed copies: a difference there may reflect disagreement between copies rather than an error on a single printed bill. A few different bills also share the same week number; the table and detail chart list each one with its dates.
Because of these choices, and because the data continue to change, figures here can differ from the archived analysis published with our article on arithmetic accuracy.