Reading between the lines part 2: Some ‘equal groups’ are more equal than others

Selection bias – some ‘equal groups’ are more equal than others The groups of participants receiving interventions should be equal, otherwise confounding variables might give one treatment an advantage over another. If there is a systematic reason for this, the study is at risk of selection bias.   Randomization (sequence generation) The first consideration is […]

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Guest Blog: The end of systematic reviews?

So the titles intentionally provocative and NOT the brainchild of the post’s author (@JRBTrip of @TRIPdatabase) … but Jon has provided us at the Archives with a paediatric-orientated version of the new TRIP rapid-review system. Read on to find out more, and comment / tweet us your thoughts … Bob Phillips for @ADC_BMJ Trip Rapid […]

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Debating devices

It’s really hard to persuade people that devices need evaluation like drugs do. This might be to do with the physical nature of a device: after all, if you can see the new cannula attachment, or special breathing mask, you know what it’s doing and what it must be making. Or it might be in […]

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StatsMiniBlog: Bland Altman Plots

Measuring things is what we do lots of, and we often want to measure things with a new machine. New, faster, shinier, cheaper, less invasive or more colourful … but we are almost always sold it as being highly correlated with the reference standard (p<0.001). Think – what is this correlation and p-value telling us? […]

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Before, and after.

In the world of non-randomised studies there are a bucketload of variants, a common one that we see if the ‘before and after study’. This is, on the face of it, a sensible approach. Do your ‘thing’, then change stuff, do the ‘other thing’. Monitor something important you hope to change, and then if it […]

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