EC255 Lecture Notes - Lecture 3: Standard Deviation, Average Absolute Deviation, Central Tendency
Document Summary
Measure of central tendency: yield info about the centre or middle part of a group of numbers. Info like average p/e ratio, middle p/e ratio, and most frequently occurring p/e ratio. The mean, median, mode, percentiles and quartiles. Arithmetic mean: average of a group of numbers sum/ number of numbers. ** n is population, n is sample , greek letter is sum of numbers. Median: the middle value of an ordered array of numbers. If there"s an even amount, find the average of the two numbers. Used to measure central tendency for nominal-level data. Measure of variablilty: describe the spread of a set of data. Range: difference between the largest value of a data set and the smallest value of the set. The distance to the outer bounds of the data set. Con: it is affected by extreme values. Data are at least interval- level data. Deviation from the mean: subtract the mean from each data value (x-u)
