These two words, though often used synonymously are different – do you know how? It’s actually not that difficult. Complicated = made of lots of parts, but “logical and rational” — like a car engine, 10001 piece jigsaw of the Gobi desert, or (dare I say it) a heart Complex = constructed with pieces with […]
Category: stats
StatsMiniBlog: Causal Analysis
A while back, we looked at propensity scores as a way of adjusting / controlling for confounders in non-randomised designs. Another approach is the hypothesis-driven estimation of an ‘instrumental variable’: a measurable feature which causes* an outcome to occur through the agency of another. Uh? In the olden days (before smartphones, WiFi and email addresses that […]
StatsMiniBlog: Cronbach’s alpha
When you’re next handing out your questionnaire in clinic, or on the wards, or sit out in the library assessing the results of a recent clinical study, will you be asking about the quality of the questionnaire you’re using or reading about? Of course. I should have realised you will. Though you might just have […]
StatsMiniBlog: Surrogate, proxy or process?
When we look at treatments for children’s ill health, we tend to be stuck in a pleasant dilemma. We normally want to use treatments to stop kids dying, and to make them better quicker – but it’s uncommon for children to die, and they’ll often get better anyway. So we end up using alternative outcome […]
StatsMiniBlog: Will Rogers Phenomenon
The American humorist, Will Rogers, was reported to have said (of the migration of folk from Oklahoma to California): When the Okies left Oklahoma and moved to California, they raised the average intelligence level in both states While this is a deeply unkind comment reinforcing geographical stereotypes, it does a neat job of capturing an […]
Guest Blog: Sampling bias and randomisation
The blog series is expanding! No doubt soley inspired by now running the magnificent @ADC_JC, @davidking83 has taken up the challenge of exploring a critical appraisal nugget/thorn in response to an appraisal session. You too could be part of our team – tweet @ADC_BMJ or find us on Facebook to get in touch – but for now, let’s […]
StatsMiniBlog: Spot on, time and again.
“Spot on!” is a rather anachronistic and very Anglophile phrase, redolent of croquet lawns, tweeds and well designed woven straw hats. It’s no wonder we tend to use – if we are being technical – the word “accurate” instead. But should we be using the word “precise” to make ourselves sound all academic? And what’s […]
StatsMiniBlog: Incidence and Prevalence
There are two relatively simple terms that get splattered about and are sometimes confused and can cause all sorts of difficulties. Incidence – the number of people who develop a condition in a specific period of time. (I think of this a bit like an ‘incident’ – a thing that happened.It probably has the same etymological […]
StatsMiniBlog: ROC plots
A (while ago) we published an explanatory page about ROC plots in the Education and Practice journal. There are a few great reasons why we should replicate it here: 1. So people can read it more easily 2. Because it fits into the stuttering series on diagnostics 3. It saves me having to write the […]
StatsMiniBlog: Z scores.
A recent journal club article, the exact nature of which is irrelevant, triggered a coffee-room discussion on the subject of z scores, which although often understood in relation to Bone Mineral Density reports are otherwise a statistical challenge. In particular the difficulties in interpreting them in a meaningful way were lamented by our team. […]