Thank you Alison- that's really helpful.
Best wishes,
Cathy
On 01/06/2012 15:40, Alison Cooke wrote:
> Hi Cathy
>
> For a pilot RCT the attached paper recommends 30 per group, and then you add on to that according to expected level of drop out.
>
> Lancaster GA, Dodd S& Williamson PR. (2004). Design and analysis of pilot studies: recommendations for good practice. Journal of Evaluation in Clinical Practice 10(2), 307-312.
>
> Best wishes
> Alison
>
> Alison Cooke
> Research Midwife
> School of Nursing, Midwifery and Social Work
> The University of Manchester
> and
> Central Manchester NHS Foundation Trust
> Maternal and Fetal Health Research Centre
> 5th Floor, Research
> St Mary's Hospital
> Oxford Road
> Manchester
> M13 9WL
>
> Tel 0161 276 5469
>
> ________________________________________
> From: A forum for discussion on midwifery and reproductive health research. [[log in to unmask]] on behalf of Cathy Walton [[log in to unmask]]
> Sent: 01 June 2012 15:24
> To: [log in to unmask]
> Subject: Re: Advice wanted
>
> Yes- that's right and in fact we are looking back over our CS rates.
> Does seem abit chicken and egg in terms of what you need to know to do a
> power calculation as the sample needs to be big enough to detect a
> difference but also to do a calculation you need to know what difference
> you might be looking for....
>
> What about for a pilot study of the same study with the same primary
> outcome?
>
> Thank you for your thoughts.
> Best wishes,
> Cathy
>
> On 01/06/2012 15:01, Carolyn Roth wrote:
>> Right, having re-read the question, I see your point. So in effect, you
>> are looking to set the (arbitrary) level against which to judge
>> statistical significance?
>>
>> Might one way of doing it be on the basis of changes to rates over time.
>> i.e. use the LSCS rate of 1,3 or 5 years ago?
>>
>>
>> Carolyn Roth
>> Director of Undergraduate Programmes and LME
>> School of Nursing& Midwifery
>> Keele University
>> Clinical Education Centre
>> Newcastle Road
>> Stoke-on-Trent
>> ST4 6QG
>>
>> Tel. 01782 679698
>>
>>> Hi Carolyn,
>>> We have and in order to do a power calculation she asked me to try to find
>>> this out.
>>> Best wishes,
>>> Cathy
>>>
>>> On 1 Jun 2012, at 12:47, "Carolyn Roth"<[log in to unmask]> wrote:
>>>
>>>> Hi Cathy, Can't answer your question, but I would have thought you need
>>>> to
>>>> talk to a statistician with the details of the proposal to get the
>>>> advice
>>>> you need.\\
>>>>
>>>>
>>>> Carolyn Roth
>>>> Director of Undergraduate Programmes and LME
>>>> School of Nursing& Midwifery
>>>> Keele University
>>>> Clinical Education Centre
>>>> Newcastle Road
>>>> Stoke-on-Trent
>>>> ST4 6QG
>>>>
>>>> Tel. 01782 679698
>>>>
>>>>> Dear Midwifery research group members,
>>>>> I am a consultant midwife at King's College Hospital in London and have
>>>>> been a member of this group for a number of years and rarely contribute
>>>>> but always find the discussions interesting. Sadly, I don't get to do
>>>>> much research in my job, as it really isn't easy to have time for it.
>>>>> However, recently I have been involved in the planning of 2 possible
>>>>> RCTs and would like to pick the brains of the esteemed members of this
>>>>> list.
>>>>>
>>>>> Would anyone have any suggestions for what would be a clinically
>>>>> significant % point reduction in the casaerean section rate if used as
>>>>> a
>>>>> a primary outcome?
>>>>> If so, can you direct me to any evidence or reference that might be
>>>>> useful to base this on?
>>>>>
>>>>> Many thanks,
>>>>> Cathy Walton
>>>>>
>> Carolyn Roth
>> Director of Undergraduate Programmes and LME
>> School of Nursing& Midwifery
>> Keele University
>> Clinical Education Centre
>> Newcastle Road
>> Stoke-on-Trent
>> ST4 6QG
>>
>> Tel. 01782 679698
> >
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