Writers in OSH publications -- this one excepted -- often start articles with aggregated figures on the billions a type of accident or illness costs the UK, European or even world economy.
However immediately impressive they are, these telephone number totals demand a leap of imagination (or some quick-footed mental arithmetic) to work out their local implications. Better to save your audience the trouble.
If you want to persuade a board of directors to fund a mental health programme, try not to lean on the well-rehearsed £34.9bn cost to the economy. There are more salient ways to state the impact.
The total of 12.5 million working days lost to stress and mental illness in 2016-17 breaks down to 23.8 days per employee. It does not take much to work out what that absence costs your business for an average member of staff, plus the expense of covering their work. You are more likely to gain the attention of a finance director that way.
This principle that statistics are more impressive rendered to an appreciable scale doesn't just hold for financial cases. Joseph Stalin's observation that "One death is a tragedy; a million is a statistic" was made with the confidence and cynicism of a man who was responsible for millions of deaths and would never be held to account. But the point is valid; the detail of a single life cut short or impaired resonates more with most people than the abstraction of anonymous thousands. Writers of plays and screenplays don't anatomise the lives of crowds, they draw us into the stories of individuals.
In safety communications or training, stressing the general impact -- the 1,530 UK workers seriously injured by moving vehicles, for example -- at the expense of the particular is unlikely to stick in the mind of a forklift driver under pressure to get a load across a site quickly.
Some organisations have brought to their safety stand-downs speakers whose commitment and authenticity is underpinned by their own life-changing injuries. Others use actors to play out the calamitous effect of such incidents on family members. That's not an option for everyone, but pushing your audience to imagine the consequences of an accident is.
If you are tasked with persuading people to accept an argument or to change their behaviour, making it vivid and personal to them half wins you the battle.
There is a place for the big numbers, but whoever you need to convince, strengthen your hand by getting down to cases.