 |
 |
On 3 Lún 2009, at 14:32, Paul Elias wrote: > This is so and my learning suggests that the 95% CI (width or > precision) depends really on the sample size and the larger the > sample size, therefore the increase in information/details we have > about the distribution, and thus about the population parameter, and > the smaller is the uncertainty about its true parameter value. The > issue is that we are trying to state with a level of certainty, the > probability that the true population parameter lies in the CI lower > and upper limit. The precision of a study depends on both sample size AND the variability of the measurements. The formula for the standard error of any statistic is the variability in the data divided by the amount of data. Note that the 'amount of data' isn't the sample size but the square root of the sample size, hence I've used the term 'amount of data'. Ronan Conroy ================================= [log in to unmask] Royal College of Surgeons in Ireland Epidemiology Department, Beaux Lane House, Dublin 2, Ireland +353 (0)1 402 2431 +353 (0)87 799 97 95 +353 (0)1 402 2764 (Fax - remember them?) http://rcsi.academia.edu/RonanConroy P Before printing, think about the environment