I. FUNDAMENTALS -- A. Statistics and Methods Flashcards
Mean
A measure of central tendency. The arithmetic average of a sample or population, or the expected value of set of probabilities.
Formula of Sample Mean
Formula of Population Mean
Formula of Expected Value of a Set of Probabilities
Median
A measure of central tendency. The value at the 50th percentile (midpoint) of a sample or population.
Mode
A measure of central tendency. The value that occurs most frequently in a sample or population.
Standard deviation
A measure of spread of a sample, population, or set of probabilities. The square root of variance. Empirical rule says that, for a normal distribution, approximately 68% of observations are within +/- 1 standard deviation of the mean, and approximately 95% of observations are within +/- 2 standard deviations of the mean.
Formula of Sample Standard Deviation
Formula of Population Standard Deviation
Formula of Standard Deviation of a Set of Probabilities
Variance
A measure of spread of a sample, population, or set of probabilities. Standard deviation squared. Cannot be negative.
Formula of Sample Variance
Formula of Population Variance
Formula of Variance of a Set of Probabilities
Covariance
A measure of how things move together. Just a directional measure (positive value means that things move in the same direction and negative value means that things move in opposite directions).