What is statistics: how did a science of "affairs of state" turn into the language of numbers?

Bobur opened a barbershop and for one week wrote down how many customers came each day: Monday 12, Tuesday 15, Wednesday 9, Thursday 14, Friday 20, Saturday 25, Sunday 10. From these seven numbers he can learn a lot: how many people come on average, on which day more barbers are needed, on which day it is possible to take time off. The name of the art of drawing conclusions from numbers is statistics.

What is statistics?

Statistics is the science of collecting data about mass phenomena, organising it, analysing it and drawing conclusions. Nobody can say when a single customer will come, but data on hundreds of customers reveals a clear pattern.

We can see this in Bobur's numbers:

• Arithmetic mean: (12 + 15 + 9 + 14 + 20 + 25 + 10) / 7 = 105 / 7 = 15 customers a day.
• Median: we arrange the numbers in ascending order: 9, 10, 12, 14, 15, 20, 25. The one in the middle is 14.
• Conclusion: on Friday and Saturday there are considerably more customers (20 and 25), so an extra barber is needed on those two days.

Statistics has two faces: one is collecting data (counting, surveys, registers), the other is understanding it (averages, change, relationships).

Where does the word come from?

The root of the word goes back to the Latin word status, "condition" and "state". According to the Merriam-Webster dictionary, the German Statistik originally meant "the study of political facts and figures". The Online Etymology Dictionary also adds the Italian word statista "one skilled in statecraft" to this family.

According to the same dictionary, the German word was popularised, perhaps even coined, by the scholar Gottfried Achenwall (1719–1772) in his work of 1748. In English the word is recorded from 1770 and was originally used in the sense of "the science dealing with data about the condition of a state or community".

So statistics was originally needed in order to know the state: how many people, how much land, how big the harvest. Later it became a general science that studies any mass data.

Why it is needed: its function and purpose

The main purpose of statistics: to draw reliable conclusions from mass data and help make decisions based on numbers instead of guesses. It performs the following functions:

1. For planning. Bobur decides how many barbers to put on each day by looking at the numbers.
2. To see change. Did sales grow this month, or was it just one lucky day: statistics helps to tell the difference.
3. To know without asking everyone. By studying a selected group, it is possible to draw a conclusion about the whole population.
4. For the state and society. Official statistics figures serve as the basis for government decisions.

Who it works with and who contributed

Statistical data is used by accountants, finance specialists, economists, auditors and government bodies. Businesses themselves also submit reports for official statistics.

To read how the science took shape, here are the history articles: «From clay tablets to the Domesday Book: why were people counted in ancient times?», «The London Bills of Mortality: how did statistics become a science?» and «Florence Nightingale: how did a nurse change army hospitals with figures and a diagram?». The links are at the end of the page.

In the next lesson

In the second lesson we will look at how statistical data is collected and what types of observation there are.