If your data span a wide range of values, it can be easier to visualize the results when you make one of the axes logarithmic. Distinguish between transforming your data to logarithms (which creates a new results table) from choosing a logarithmic axis (which only stretches the axis, without altering your data).

What is a logarithmic axis?

How to: Create a log axis

Logarithmic axes cannot contain zero or negative numbers

Regression fits the data, not the graph

When to use a logarithmic axis

Advice: Bar graphs with log axes rarely make sense

Graphing logarithms - different than using a log axis

A review of logarithms