Confidence interval and standard error of the mean

Question 1

What is meant by the “confidence interval” and “confidence level”

Answer 1

Confidence interval = a range of values within which the true effect of intervention is likely to lie

Confidence Level = The likelihood of the true effect lying within the confidence interval is determined by the confidence level.

E.g. 95% confidence level means that the confidence interval should contain the true effect of intervention 95% of the time.

Question 2

What is the standard error of the mean (SEM)

Answer 2

measure of the spread expected for the mean of the observations - i.e. how ‘accurate’ the calculated sample mean is from the true population mean

Question 3

What happens to SEM as the sample size increases?

Answer 3

It decreases