The recruitment of 60 practices is required assuming a practice-drop-out rate of 10%.
We assume a practice size of 10,000 people, amongst whom there will be approximately 3,500 people aged 50 or more to whom these interventions will be mainly relevant and on whom the calculations are based.
Assuming an average practice size of 5 GPs, we estimate around 160 200 GPs and Nurse Practitioners will take part.
Assuming an average practice list size of 6,000, that 15% [ 39] are aged between 20 and 40 (most common age range for colposcopy), and that 70% have not experienced colposcopy, 630 patients per practice will be eligible as controls [Figure 1].
On the basis of our pilot data (3.2% of the age group being suitable and consenting) and assuming an average practice list of 4500 with 18% of people aged 50 69 (Office for National Statistics, 2004), 23 100 people from 29 practices were estimated to be required to identify 700 eligible participants consenting to colonoscopy and MMP9 determination.
The common practice of assuming a dominant pattern of inheritance can cause serious losses of power in the presence of any recessive, or modest dominant, effects.
Required number of person-years and GP practices (assuming an average GP practice size of 6,000 patients) by country, based on the relative populations of the 4 countries.
This indicated that for 30 practices (assuming a non-response by 10/40 practices) over 40 weeks, 5400 women could be identified, 3300 invited and 1800 agree.
Assuming therefore a conservative 1000 eligible patients per practice of average list size 6000, and adjusting for clustering of patients within practices, assuming a conservative ICC of 0.05 [ 43, 44] the sample size required was 27,768 per arm, equivalent to 28 practices per arm.
The usual journalistic practice of assuming a neutral posture simply won't suffice for these readers, she believes.
Most of us, when we talk about stretching, mean the practice of assuming a pose, like bending over to touch our toes or leaning against a wall to stretch our hamstring muscles, and holding that position until the stretching feels uncomfortable, usually 30 seconds or so.
