STA 2023 Lecture Notes - Lecture 31: Normal Distribution, Confidence Interval, Standard Deviation
Document Summary
Section 7. 2 confidence intervals for the mean when. The value of the standard deviation, when it is not known, must be estimated by using s, the standard deviation of the sample. When s is used, especially when the sample size is small (less than 30), critical values greater than the values are used in confidence intervals in order to keep the interval at a given level, such as 95% These values are taken from the student t distribution, most often called the t distribution. The symbol d. f. will be used for degrees of freedom. Subtracting 1 from the sample size finds the degrees of freedom for a confidence interval for the mean. A sample of 10 networking sites for a specific month has a mean number of visits of. Find the 99% confidence interval of the true mean. Because n<30 and standard deviation is unknown, we will use the t-distribution.
