# Stats - Histograms

> Source: https://ollybritton.com/notes/a-level/maths/topics/histograms/ · Updated: 2020-11-17 · Tags: stats, year-1, school

##### What sort of data do you normally use bar charts with??
Discrete data.

##### What sort of data do you normally use histograms with??
Continous data.

##### At GCSE, what was the frequency in a histogram??
The area of a column.

##### Why is the GCSE definition of a histogram incorrect at A-level??
The area of the bars is not always frequency; it can be scaled by a scaling factor.

##### If the frequency reads $30$ from a table, but is $60$ on a histogram, what is the scaling factor??
$$
\frac{60}{30} = 2
$$

##### What is a frequency polygon??
A historgram where you draw a line from the midpoint of each interval at the top of a bar.

##### In a frequency polygon, how should you deal with there being no column for a group of frequencies??
Make the line touch the $x$-axis.

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