STA-1013 Lecture Notes - Lecture 9: Confidence Interval, Standard Deviation
Document Summary
A confidence interval is a range of values likely to contain the true value of the population mean. 95% confidence interval for a population mean: the margin of error for the 95% confidence interval is. Margin of error= e~ 2s/ square root of n. Where s is the standard deviation of the sample: we find the 95% confidence interval by adding and subtracting the margin of error from the sample mean, the 95% confidence interval ranges. From (x-bar margin of error) to (x-bar + margin of error) X-bar e < u < x-bar + e. Interpreting example: (cid:862)we are (cid:1013)(cid:1009)% (cid:272)o(cid:374)fide(cid:374)t that the populatio(cid:374) (cid:373)ea(cid:374) for protei(cid:374) i(cid:374)take of all. A(cid:373)eri(cid:272)a(cid:374) (cid:373)e(cid:374) is (cid:271)et(cid:449)ee(cid:374) (cid:1010)(cid:1013). (cid:1012) a(cid:374)d (cid:1012)(cid:1008). 2 gra(cid:373)s. (cid:863) Choosing sample size: solve the margin of error formula e~2s/square root of n for n, n= (2s/e)^2. In order to estimate the population mean with a specified margin of error e, the size of the sample should be at least:
