STAT 100 Lecture Notes - Lecture 13: Sampling Distribution, Interval Estimation, Point Estimation

• School: University of Maryland
• Department: Statistics and Probability
• Course: STAT 100
• Professor: Cremins

Document Summary

Con dence intervals when sigma is known for an unknown population. A con dence interval is point estimate +/- margin of error. Reasoning of statistical estimation about the mean con dence interval about the mean. 1. 96 x n < (x-bar) < + 1. 96 x n. Same as (x-bar) - 1. 96 x n < < (x-bar) + 1. 96 x n. Thus a 95% con dence interval for the population mean is: (x-bar) +/- 1. 96 x n. This is in the form: (point estimate) +/- (margin of error) The margin of error here is 1. 96 x n. If we wanted to compute a 90% con dence interval, or a 99% con dence interval, etc. , we would just need to nd the right standard normal value. In general, for a (1- ) x 100% con dence interval, we need to nd the critical value z (a/2") i. e. , the z-score such that the area to the right of it is /2: