Sample size calculation for prospective observational study studying outcome of an intervention?

#1
Hello everyone,
I am submitting proposal for thesis and I need help with the sample size calculation.

My study is: to study the outcome of "x" intervention in "y" disease
The prevalence of disease is 2.6%.

How do I calculate the needed sample size? What else information do I need from the previous study?

Thanks in advance.
 

hlsmith

Less is more. Stay pure. Stay poor.
#2
What is the intervention and what is the outcome? How are they formatted? Traditionally X represents intervention and y the dependent variable (outcome).
 
#3
Functional outcome is a score and intervention is a type of surgery and disease is a fracture. The prevalence of disease is around 2.6%.
 

hlsmith

Less is more. Stay pure. Stay poor.
#4
You have three things here. Surgery is the intervention, what do the other two variables represent? How is score formatted and what is its distribution?
 
#5
Hi hlsmith, I mean:

I need to study the outcome of an intervention in a disease. I will be doing a prospective observational (longitudinal) study in a single cohort (I am not sure if i'm correct - I mean, I will be taking only a single group of diseased undergoing the proposed intervention). The prevalence of the disease is ~2.6%. The mean +/- SD of the measured outcome in previous study is 253 +/- 9.
So, How will I proceed further with the sample size calculation?
Any help will be greatly appreciated.