STAT 400 Lecture Notes - Lecture 3: Interquartile Range, Variance, Standard Deviation
28 Jun 2017
School
Department
Course
Professor
Document Summary
The formula for variance is, variance is represented by (cid:2870) (lower case sigma squared) (cid:2870)=(cid:883) (cid:4666) (cid:4667)(cid:2870) =(cid:2869) where is the observation and is the mean for the data set: sd is the square root of variance. That is, = (cid:2870) variation or dispersion in a data set. Standard deviation: the standard deviation is a measure that is used to quantify the amount of. Variance-a measure of how far a set of random numbers are spread out from their mean. Random variables and sample variance regular variance: for a random variable, the variance, denoted as var(x) is the same as, for sample variance, denoted (cid:2870), the formula for variance is slightly different. =(cid:2869) where is the observation and is the mean for the data set. We use that because otherwise we"d have a bias in the estimation of the population variance. Range, iqr and 5 number summary: sample range is the largest observation- smallest observation.
