Separating how bad a harm could be from how likely it is to happen

Severity and probability answer different questions, and a trowel shows why that separation matters. Severity asks: if a hand slips while digging, what injury could follow, given the pointed tip, the force of the thrust, and the closeness of the other hand. Probability asks: how often does that slip occur, given wet soil, gloves, tired arms, and the way the trowel is gripped.

Keeping the questions apart prevents a common distortion. A dramatic injury does not become likely just because it is frightening, and a frequent small cut does not become trivial just because it heals quickly. Each question deserves its own evidence and its own sentence in the scoring note.

To judge severity, describe the worst credible outcome, not the worst imaginable one. A trowel tip driven by a full digging thrust toward an ungloved hand could cause a deep puncture, while a tip brushing a gloved palm during light weeding could cause a scratch. The scoring note should say which outcome it is scoring and why that outcome, rather than a more extreme fantasy, was chosen.

Body part, force, and sharpness all belong in that description. A cut to a fingertip, a puncture near a wrist, and a scrape on a knee are not interchangeable, and a severity judgement that lumps them together will mislead every later decision about guards, handles, or warnings.

Illustration: a supplier imagines 100 digging sessions and supposes that in 20 of them, in round illustration terms, a hand slips at least once because of wet soil or a loose grip. Those figures, as presented in Separating how bad a harm could be from how likely it is to happen, are invented, not measured. They are useful only because they force a question: is a slip in a fifth of sessions frequent, occasional, or rare for this kind of work, and what handling or observation would support a different view.

Probability also changes with context. Digging in dry, loose soil with a firm handle is not the same as levering stones in wet clay with cold hands. The scoring note should therefore give probability per context, not a single number that pretends all digging is alike.

When the two judgements are combined, the combination should be explained, not just multiplied in silence. A severe but rare harm may call for a design change, while a minor but frequent harm may call for a grip improvement or a clearer instruction. The right response depends on which side of the pair is driving the concern.

• Write severity and probability in separate columns with separate reasons.
• Note the context for each probability judgement, such as wet soil or gloved hands.
• Explain what action follows from the combination, and what would change it.
• Flag any judgement resting on guesswork so it can be revisited after handling.

One trap is to let severity borrow probability's clothes. A reviewer who has seen a shocking injury photo may score a rare puncture as if it happened weekly, and then recommend drastic action that distracts from the frequent cuts actually occurring. Another trap runs the other way: a reviewer who has dug for years without injury may score a real puncture risk as negligible, because personal luck is mistaken for evidence.

Both traps share a cause, which is scoring from feeling rather than from description. The remedy is to write the sequence, the body part, and the context before any score, so a second reviewer can challenge the description instead of arguing about a number.

A finished scoring note for the trowel should let a reader trace each combined judgement back to its two parents. If a combined judgement cannot be traced, it should be rewritten, even if the final action seems sensible, because an untraceable judgement cannot be updated when the trowel changes.

Revisit the scores when the tip is resharpened in production, when the handle material changes, or when gardeners report slips. Each revisit should keep the old scores visible beside the new ones, so the history of the judgement remains part of the file.