The Results section of the paper contined the following table:
Variable | Wet (intervention) (n=450) | Dry (control) (n=420) | P value |
---|---|---|---|
Mean (SD) age (years) | 55.9 (16.6) | 56.5 (16.2) | 0.58 |
Male patients | 249 (55) | 208 (50) | 0.08 |
Mean (SD) days to removal of sutures | 8.6 (2.2) | 8.6 (2.2) | 1 |
Presence of diabetes | 9 (2) | 14 (3) | 0.2 |
History of other medical condition* | 8 (2) | 10 (2) | 0.5 |
Treated with 1% lignocaine adrenaline | 435 (97) | 411 (98) | 0.3 |
Excision of skin cancer | 294 (65) | 289 (69) | 0.3 |
Excision at lower limb | 112 (25) | 106 (25) | 1 |
* Chronic obstructive pulmonary disease (n=8), anaemia (1), "aspirin" (2), "steroids" (3), "warfarin" (2), ischaemic heart disease (1), and peripheral vascular disease (1). |
Question 2: Is this a null hypothesis which should be tested in a randomised trial? What would it mean if one of these tests was significant?
The subjects were randomised into two groups. This means that each treatment group is a random sample from the same population. The null hypothesis is therefore true.
We are testing a null hypothesis which we know to be true. This is a complete waste of time. If a difference is significant it must be one of the one in every 20 tests of a true null hypothesis which is significant.
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Last updated: 31 July, 2006.