We all know that blood pressure is a continuous variable. We measure it with a sphygmomanometer and, within the limits of measurement and its extreme range, blood pressure can be anything: 80/40, 110/60, 125/85, 155/105, or 210/160—though the first and last of this list not for long, one hopes. This hasn’t stopped generations of doctors from trying to define a cut-off above which one is hypertensive, a cut-off that sinuously moves up and down, but mainly down, in response to megatrials, meta-analyses, pressure from Big Pharma, and Deep Thought from NICE, but which has long ago left behind what I was taught: the normal systolic is 100 plus one’s age.

There are lots of continuous variables: serum sodium, glomerular filtration rate, cardiac output. There are lots of other variables that mimic continuous variables, but aren’t really. Pain for one. You can measure pain by category as none, mild, moderate, severe; or you can pretend that it is a continuous variable by waving a 10cm line at patients and asking them to put their pain on the line. This gives wonderfully precise measurements—0.4, 3.5, 7.8, 9.2—but we fool ourselves if we think this gives any more information than the simpler categories. We could do the same with morale: indeed David Cameron’s first annual survey of happiness revealed that the average Briton rated their life satisfaction as 7.4 out of 10.

My scanning of the internet tells me something different. You might think that morale is a quasi-continuous variable like pain, but it is a binary variable, like male/female. And the two categories, or states, are sky high and rock bottom. There are no other gradations. What is more, the category is determined by profession. Taking part in a sporting event, morale is always sky high. Being a doctor, morale is always at rock bottom: “…professional morale has hit rock bottom” (1995); “…the Government’s market approach has led to rock bottom morale…” (1996); “…a hospital doctor warned [Blair] yesterday that morale was at ‘rock bottom’” (2001); “…morale is at rock-bottom and patients felt unsafe…” (2004); “…it is commonplace to debate the whys and wherefores of rock-bottom morale in the profession” (2006); “Does the [Health Secretary] think that the rock bottom morale among healthcare professionals…?” (2007); “…unprecedented workloads and high levels of admissions had left staff morale at ‘rock bottom’” (2013).

And there’s no let-up: on 8 January this year, Paul Routledge in the Daily Mirror “…heard chilling evidence of over-worked staff, of privatisation of services, of job losses, of rock bottom morale.”

In 2001, Polly Toynbee quoted the BMA saying, “Morale has never been lower” (and noted that everyone says so when asked by their Union). Indeed. Nor has it ever been higher. It’s just bumping along the bottom. And nobody’s fooled. When metaphor descends to cliché, the world yawns and turns away.

Competing interests: I have read and understood BMJ policy on declaration of interests and declare that my only competing interest is my co-authorship of a book about medical English.

Neville Goodman is a retired consultant anaesthetist and a writer, and co-author of a book on medical English.