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archimedes

StatsMiniBlog: Kappa

16 Jul, 14 | by Bob Phillips

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After a short pause while brain cells were diverted elsewhere, we’re returning with the critically acclaimed (well, slightly positively tweeted) StatsMiniBlog series.

(As an aside – do let me know via comments, Facebook or Twitter if there’s an issue you’d like to see covered)

Kappa (κ) is a measure of agreement, usually between two observers of a dichotomous outcome although there are variants for multiple observers.  It gives you a measure of what agreement you see that is ‘beyond chance’

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“Compared to standard care”

9 Jul, 14 | by Bob Phillips

There’s a decent argument in the analysis of quantitative studies of therapies, particularly using RCT designs, that says that we should be looking at the totality of unbiased evidence (systematic reviews) rather than looking at individual, cherry-picked, studies. The best estimate from this come from a pooling of all the results: meta-analysis.

There’s a challenge to this, though, when the comparisons are not quite the same. In the case of trials of drug A vs. B, C, D and E it can be quite easy to spot (and then perhaps undertake a network meta-analysis to address the issue). When the trials are A vs. standard care it’s a greater challenge to see if & how “standard care” varies.  more…

The despair of the box-ticking paediatrican

1 Jul, 14 | by Bob Phillips

So, as the annual assessment of learning by paediatric trainees reached fever pitch in many ares of the UK, a question rang out across Twitter:

In (trainees approaching ARCP), does (shoehorning logbook to curriculum) compared to (reflecting on clinical experiences) improve outcomes?

And while this, I feel, is more of an emotional outpouring to garner peer support, love and recognition of the need for coffee rather than an evidence request, there are some data supporting the use of work based assessments and e-portfolios

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StatsMiniBlog: Rethinking meta-analysis

15 Jun, 14 | by Bob Phillips

StatsMiniBlogThe concept of meta-analysis was addressed previously, essentially pulling together data from a range of different studies and assuming that they are only (fundamentally) different by chance, or differ by real things too as well as chance, and you’re seeking an average effect across the average of these differences. The maths under this takes each study as an item, and comes up with a weighted average of the effect sizes.

There’s another way of looking at this: more…

When a test isn’t a test

8 Jun, 14 | by Bob Phillips

There are many reasons why we request tests, in medicine. One imaginary patient’s journey picks up a number of them.

Take a patient who presents with a painless lump on their arm, who’s tired and a bit pale & washed out. You might send a series of blood tests, including a full blood count to diagnose anaemia. You may also request an ultrasound of the lump, which may show an ugly mass with features consistent with sarcoma. Your friendly local plastic sarcoma surgeon might do a biopsy for you after an MRI, and the histopathologists confirm it’s a rhabdomyosarcoma.

All these tests are aimed at making a diagnosis: to clarify if the patient in front of us has, or does not have, the condition.

The oncologist who then takes up the patient’s care will move to undertake a series of further investigations; more…

Different but similar. Life-limiting long-term conditions in children.

25 May, 14 | by Bob Phillips

One of the great professional joys of a part-time life in or about paediatric palliative care is being made constantly aware of how much there is in the world that I know next to nothing about. (One of the great personal joys is being able to do something that improves a short life, within a multi-professional team.)

One thing that has always been a sneaking under-feeling, perhaps based in a desperate hope rather than any evidence, is that there are a core of things that children with life-limiting conditions struggle with, and that if I can keep up my skills in constipation management, pain relief, emergency seizure control and sleep hygiene I’ll be able to do some good.

Well, this month in the Archives there’s a reassuring paper that sort of agrees with my unstructured assessment. more…

Boundary spanning in collaborative networks. Asleep yet?

21 May, 14 | by Bob Phillips

Sometimes you need a massive push to take you beyond a title into reading a paper.

(Well, when I say sometimes, I mean ‘most times’. Often, the push can be the patient that has driven you to start looking. Sometimes the push is the grand round or journal club you need to present. Rarely, it’s because you just want to expand you mind a little more than “high CO2, increase frequency” … )

Bridges, brokers and boundary spanners in collaborative networks: a systematic review” actually contains a mass of really deeply interesting ideas. more…

StatsMiniBlog: ROC plots

19 May, 14 | by Bob Phillips

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 same thing in different words.

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Underpowered and over here.

14 May, 14 | by Bob Phillips

From @aLittleMedic

We’re great fans in the Archimedes blog of trying to get people to think about the meanings and impacts of research, like asking What would Jack want and not believing p-values. One key idea is that of an ‘important clinical difference‘ (see – avoided significantly …) that is essential in working out if a trial is telling you two treatments really are equivalent, or if the study is just underpowered.

If you’re designing a trial you’ll be wanting to be very very sure that this difference, that you’re gong to base all your study numbers upon is, made upon the best possible grounds. Aren’t you.

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Let me tell you a story … journal clubs as literary criticism

23 Apr, 14 | by Bob Phillips

From the worlds greatest comic

 

 

Have you ever been to a journal club and had the slight suspicion that what you are addressing isn’t quite on-target? (Ever been part of #ADC-JC and realised that most of Twitter appears to be whispering at the back and passing notes to each other?) Ever considered if journal club really is a scientific pursuit?
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