Histogram

Histograms show frequency distribution: how often a value is present in a data set. Each bar covers a range of values, and the bar's height is defined by how many data points are in that range.

The shape of the distribution and the presence of outliers, can give you a lot of information from the dataset, and even provide an indication on the quality of the data set.

Usage guidelines

When to use

Questions you can answer

• What's the distribution of this data set?
• What's the shape of that distribution?
• Are there any outliers?
• What are the most frequent values?

When not to use

• If the data is distributed in categories, like countries, instead of a continuum, like policy density or premium amount, use a bar chart instead.
• If you want to see how a category evolves over time, a line chart is a better choice.

Usage recommendations

Choose an appropriate number of bins. Too few bins will make it hard to discern any pattern in the data, while too many bins can add too much noise.

Don't use anything other than zero as the baseline. Changing the baseline can have a dramatic effect on the interpretation of data.

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