In a previous post I muttered about how unhelpful sensitivity and specificity are to practicing clinicians, and how what we really want to know are the predictive values of a test. Remembering the Table Really diseased Really not diseased Test +ve A B 1.. A/(A+B) Test -ve C D 2.. C/(C+D) 5.. […]
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Subjective = meaningless.
So, that’s a deliberately provocative title (which I was assured by a friend in social marketing was a good way to generate blog traffic) … but it’s vaguely accurate. Does subjective = meaningless? […]
Breath deep, breathe hard, breathe long.
I have to admit to being drawn to systematic reviews of things I don’t really understand. So when this editors choice review of ventilator types for neonates sprang up, I did get tempted to look … Now I last did neonates >10 years ago I occasionally wake up, cold sweats, vividly remembering NICU The same […]
Sensitivity and specificity
Sensitivity and specificity are those sorts of things that can really get knickers twisted up something rotten. They sound like something you should be able to understand, they get used as if you understand them, and then you realise … it’s not quite as you thought … Really diseased Really not diseased Test […]
Basics: Top 5 tips for evidence based paeds
Hot on the heels of my office next door neighbours SoMe course we’re off with a ‘Top Tips’ post. (Anyone who hates the cheesy format can comment below or tweet us @ADC_BMJ.) Please imagine a racing, 5-years-before-you’re-reading-this-pop-tune as your background music. 1. Know your question Know what you’re asking. And know why you’re asking it. […]
If the patient knows more than you do …
I spend some of my time working in a hospice for children and young people, and much of that time I know I am looking after patients who, themselves or their parents, know more about their condition than I do. Dealing with this – when I’m asked to review someone who has something I know I should […]
StatsMiniBlog: Odds and Probabilities
There’s something that is frequently wittered about but the odds are you’ve never really been bothered enough to care if there’s a difference between ‘probability’ and ‘odds’ (like relative risk and odds ratios). There are great reasons for this. Coffee, beer, ‘Take Me Out’ or a crash call to labour ward are four, for example. […]
Diagnostic test accuracy
The main things we look for when examining a new diagnostic test are “Is it as good as, or better than our usual one”, “Is it quicker?”, “Is it cheaper?” and “It is easier for patients/less dangerous?” While the latter three questions can be assessed by asking the folk who do the test, asking the […]
Differential Diagnosis
The essential elements of a differential diagnosis study are, like most of critical appraisal, really simple and straightforward. You need to start with a bunch of children/young people who turn up with the symptom, or symptom-complex, you’re interested in. Ideally, you need these folk to not already be known to have something, to attend a […]
StatsMiniBlog: Subgroup or sensitivity analyses?
Perhaps becoming a little obscure, but there are some folk in the world who become concerned about undertaking analysis in systematic reviews. Some of these are described as “subgroup” analysis, others “sensitivity”. What’s the difference, and why? […]