# Statistics

Statistics are a set of mathematical techniques to analyze numerical, categorical, and ordinal data to produce information, especially for the purpose of inferring proportions in a whole from those in a representative sample.

Numerical data, also known as quantitative data, consists of discrete or continuous data. Discrete numerical data are values that can be counted, such as a quantity; for example, the number of heads in 10 coin flips or the number of correct answers on a test. Continuous numbers are measurements in which the value may fall in between any two other values; for example, the speed of a car or a volume of water.

A car that travels from 0 to 60mph reaches all possible speeds between 0 and 60mph, which makes speed data continuous. Whereas the number of laps a car has taken on a racetrack increments by one each time, thus the number of laps is never between, for example, 1 and 2, and thus "number of laps" is a discrete value.

Categorical data, also known as qualitative data, consists of data which describes characteristics and does not have a mathematical meaning. For example: Gender, color, and favorite food are all types of categorical data. Though numbers can be assigned to categorical data, it is not valid to compare those numbers mathematically.

Ordinal data consists of a mix of categorical and numerical data, where the data fall into numerical categories. For example: a 5-points scale for product reviews is ordinal because each category is numeric and can be compared (e.g. to get an average rating).

## Deeper Knowledge on Statistics

### Averages: Measures of Central Tendency

Usage and calculations for mean, median, and mode on a set of numbers

### Data Analysis

The transformation of data to information

### Data Science

The scientific method applied to data analysis

### Dispersions: Measures of Spread

Usage and calculations for range, standard deviation, and variance on a set of numbers

### Standard Deviation

How to define, find, and use the standard deviation

### Statistical Hypothesis Testing

The art and science of stimulating demand

## Broader Topics Related to Statistics

### Data Analysis

The transformation of data to information

Fun with numbers