STAT151 Lecture 3: Stats Chapter 3 Lecture Notes

• School: University of Alberta
• Department: Statistics
• Course: STAT151
• Professor: Alireza Simchi

Document Summary

Analyze data from quantitative variables using descriptive statistics. Numerical measures of central tendency: mean, median, mode, quartiles. Numerical measures of variation: range, inter-quartile-range, and standard deviation. Suppose i have a sample of n observations y1, y2, , yn, then the mean or average is: 1 suppose: y1 = 1, y2 =0, y3 = -1, y4= , y5 = 5, = 1 + 0 + (-1) + +5 = 1. 628318, then the average of this data is. Question: is it possible to be below class average and still be in the top 10% of the class: yes, ex. 50, 50, 5(cid:1004), 5(cid:1004) 5(cid:1004), 5(cid:1006), (cid:1005)(cid:1004)(cid:1004) 18 students got 50%, you got 52% and 1 student got 100% Mean does not represent the center of the data. The class average is = 18(50) + 1(52) + 1(100) = 52. 6% The sample median of a set of measurements is the middle value when the measurements are arranged in ascending order.