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Researcher describes how he got significant results

Tom Kindlon

Senior Member
Regarding excluding outliers, see the 2nd half of my comment on this paper
Health Technol Assess. 2006 Oct;10(37):iii-iv, ix-x, 1-121.
Cognitive behavioural therapy in chronic fatigue syndrome: a randomised controlled trial of an outpatient group programme.
O'Dowd H1, Gladwell P, Rogers CA, Hollinghurst S, Gregory A.


Additional information on/context for the walking test results (from the full text):
The abstract doesn't put the walking test results in context.

In the full text, the authors say:
"The ISWT, used as a physical performance measure, has normative reference data described by Taylor and colleagues.7 Their sample of 122 healthy subjects (mixed gender and age) walked a mean of 67 × 10-m shuttles."
Contrast this figure of 67 with the results achieved:

The CBT group started at: 24.3. After six months, were at 28.5 and at 12 months were 28.9.

The changes are thus minimal compared to normal functioning.

The full text also refers to outliers being excluded:

"Five clear outlying observations were omitted from the analysis of shuttles walked. Three were very low values (0 or 2) and two were amongst the highest values (60 and 75), but were from a patient with a low baseline score (9). If these outliers were retained, the SEs increased and difference between CBT and SMC was no longer statistically significant (p = 0.17)."
Whatever about excluding the low values, I question excluding the values of 60 and 75 which are the type of scores one sees in the normal population. It is not widely accepted that nobody with CFS ever gets back to normal functioning (I don't even think the authors believe this either). It is understandable to exclude scores that don't look like they represent the real values, but there is no evidence that the scores of 60 and 75 are anything other than the real, or valid, values.

Also, the wording, "two were amongst the highest values", suggests that there were other high values but these weren't excluded.


Hoarder of biscuits
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