Why it matters in the Letby case
Visually striking rota charts can carry inferential weight beyond their content. Statistical critique focuses on how the Letby chart was constructed and presented.
Statistical explainer
How to read a rota chart
A rota chart shows nurse presence by shift. Reading it carefully requires knowing how the event set was defined, whether comparator nurses are shown on the same axis, and what shift volume each nurse worked.
Statistical analysis5Commentary
Last updated
Prosecution position
The rota chart was presented visually, with Letby's presence marked against each charted event.
Expert challenge / post-conviction reading
Statistical critique focuses on three things the chart does not show: how the event set was defined, whether comparator nurses appear on the same axis, and what shift volume each nurse actually worked. A visually striking chart can carry inferential weight well beyond its content.
What remains uncertain
This page describes how to read such a chart rather than reproducing the trial exhibit. Readers should treat it as an aid to reading the linked evidence and analysis pages, not as a substitute for the record.
Common questions
What should I look for first in a rota chart?
How the events were chosen. If they were selected because of who was present, the chart cannot tell you anything about who caused them.
Why do comparator nurses matter?
Because without them there is nothing to judge one person's pattern against. A nurse who works more shifts will be present at more events for that reason alone.
Why does shift volume matter?
Presence at events scales with how much you work. A chart that does not show shift volume invites a comparison that has not been normalised.
Is the chart from the trial reproduced here?
No. This page explains how to read one; the linked evidence and analysis pages set out what the record shows about the chart used at trial.
Related reading
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