Statistics Review: Descriptive and Inferential Statistics - Prof. Yuan-Kang Wang, Study notes of Introduction to Sociology

Download Statistics Review: Descriptive and Inferential Statistics - Prof. Yuan-Kang Wang and more Study notes Introduction to Sociology in PDF only on Docsity! 9/12/11 NEXT MONDAY WILL BE IN SANGREN 1206 SOC 2830 Outline  Basic math review  Descriptive and inferential statistics Basic over view   (sigma) is “the summation of”sigma) is “the summation of” o Xi means “the summation of all the scores”  Xi = 12, 17, 22  Xi =12+17+22= 51  Xi2= (sigma) is “the summation of”12)2 + (sigma) is “the summation of”17)2 +(sigma) is “the summation of”22)2 =144+ 289+ 484= 917  (sigma) is “the summation of”Xi)2 = (sigma) is “the summation of”12+17+22)2 = (sigma) is “the summation of”51)2= 2601  Rules of precedence o Squares and square root > multiplication and division > addition and subtraction o The rules may be overridden by parentheses  2 + 3 x 4 = 2 + 12 = 14  8 + 2 x 22/2 = 8 + 2 x 4/2 = 8 + 8/2 = 8 + 4 = 12  (sigma) is “the summation of”8 + 2) -4 (sigma) is “the summation of”3)2 / (sigma) is “the summation of”8-6) = 10 – 4 x 9/2 = 10 – 36/2 = 10 – 18 = -8 Statistical Applications  Two main statistical applications: o Descriptive statistics  “What is the average family income in Kalamazoo?” o Inferential Statistics Descriptive Statistics  Summarize variable one at a time.  Summarize the relationship between two or more variables  Data reductions: reduce a large amount of data into a few easily understood numbers  Univariate descriptive statistics include only one variable: o Percentages, averages, and various charts and graphs  Bivariate descriptive statistics describe the strength and direction of the relationship between two variables o Example: older students have higher GPAs. o “time spent studying statistics” and “final grade in statistics” o Association (sigma) is “the summation of”correlation)≠ causation  Multivariate descriptive statistics describe the relationships between three or more variables