statistics
Disclaimer: I’m not a statistician; I just have a shallow grasp of statistics. Also this page is in progress.
Statistics deals with the collection, organisation, analysis, interpretation, and presentation of data.
types
- Descriptive statistics summarise data
- Inferential statistics make predictions
| type | examples |
|---|---|
| binary | yes or no |
| categorical | film genre |
| count | number of pushups |
| number | 42 |
| ordinal | low, medium, high |
terms
mean
The arithmetic mean is the sum of all values in a given set divided by the number of values in that set:
Other types of means:
- The geometric mean is the root of the product of all values in a given set
- The harmonic mean is the reciprocal of the arithmetic mean of the reciprocals of a given set. Useful for finding the average rate
- The root mean square is the square root of the arithmetic mean of the square in a given set
standard deviation
The standard deviation (σ) of a set determines the amount of variance in its values.
other
- The median is the middle number in a sorted dataset (smallest to largest)
- The mode the most frequent item of data
correlation
Covariances measures how one variable relates to another variable. Postive covariances indicate that the two variables move in the same direction; conversely, negative covariances indicate they move in opposite directions.
Correlation is basically just covariance but normalised. You’ll only get correlation values that range from -1 to 1. A correlation of 1 is a positive correlation, -1 is a negative correlation, and 0 means no correlation.