SOC 411 Lecture Notes - Lecture 4: Interquartile Range, Standard Deviation
29 Apr 2016
School
Department
Course
Professor
Document Summary
A measure of variability tells you how spread out a distribution is around some centre point. We will discuss three measures of variability: range, inter-quartile range (iqr), and standard deviation. The range" reports the distance between the highest (maximum) and lowest (minimum) values in a distribution. e. g. students" commute time had a range of 135 minutes. For ordinal variables, this distance is often not meaningful. Instead, we report the highest and lowest values. e. g. answers ranged from disagree to strongly agree . The interquartile range tells us about the spread of the middle 50% of the cases. It tells us the distance between the 25th percentile and the 75th percentile. Percentiles are the point at which a certain number of cases are above or below it. The 10% percentile has 10% of cases below it, and 90% of cases above it. The 40% percentile has 40% of cases below it, and 60% of cases above it.
