QMS 202 Lecture Notes - Lecture 2: Binomial Distribution, Statistical Parameter, Guesstimate

• School: Ryerson University
• Department: Quantitative Methods
• Course: QMS 202
• Professor: Nursel Ruzgar

Document Summary

Confidence intervals for the population mean, : 10. 2 when population standard deviation is unknown. Confidence intervals for the population proportion, . In virtually all real-world business situations, is not known. If there is a situation where is known, then is also known (since to calculate you need to know . ) If you truly know there would be no need to gather a sample to estimate it. If the population standard deviation is unknown, we can substitute the sample standard deviation, s. This introduces extra uncertainty, since s is variable from sample to sample. So, we use the t distribution instead of the normal distribution. Assumptions: population standard deviation is unknown, population is normally distributed, if population is not normal, use large sample. Confidence interval estimate: where t /2 is the critical value of the t distribution with n -1 degrees of freedom and an area of /2 in each tail. The t is a family of distributions.