Question

- Sampling variation and the standard error

- Confidence interval for the meanInterpretation of confidence interval Smaller samples
- Confidence interval using t distribution

can any one help me with those topics in biostat i have finals and im struggling just a breif summary about what important in them to know

Answer 1

Sampling Variation- it is the variance of sample mean and can be calculated by data(variance)/n,

here n is the sample size.

Standard Error- The S.E is the standard deviation of sampling distribution of sample mean it is s.d(data)/squareroot(n)

basically the confidence interval is the measure which give a certainity of confidence about the range of te unknown parameters, when we assume that the data is normally distributed then for unknown popln variance we aply t statistic to obtain confidence interval for popln parameter(mean), which can be as

x(bar)-t(n-1)(alpha/2)*s/squareroot(n)<mu<x(bar)+t(n-1)(alpha/2)*s/squareroot(n).

basically these things give the some details about unknown characteristics of population because sometimes it is not possible to obtain data for whole popln then we estimate popln characteristics on behalf of these statistic.