ECON 307 Lecture Notes - Lecture 1: Random Variable, Sampling Distribution, Standard Deviation
Document Summary
Descriptive statistics- set of techniques to describe distribution of a variable in a sample. Variable- anything that changes from observation to observation. Time series (stationary: fluctuates around same level; non-stationary: trend up or down- stock prices) vs. cross sectional. Sample is the part of the data that we observe. Distribution of a variable- shows what is possible for variable and how freq. those occur. Positive skew (right) the right tail is longer or fatter. Negative skew (left) the left tail is longer or fatter. Negative kurtosis- flatter, more like uniform; thin tail. Distribution of variable- shows what kinds of values are possible and how frequently they occur. Stock return = p1 / po 1. Median- 50% of all observations fall below this. Iqr- difference between q1 and q3- spread of variability in sample. Standard deviation- how spread out observations are around the mean. Inferential- use information from sample to find what might be true about entire pop.
