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).

Statistics Resources

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

Statistics Knowledge Graph