Logarithmic scale plots equivalent distances on the chart for
equivalent percentage changes.
A move from 100 to 200 would be the same distance on a log
chart as a move from 10 to 20.They both represent 100%
Arithmetic scale plots equivalent distances on the chart for
equivalent numeric or dollar changes.
On an arithmetic chart, a move from 100 to 200 would show ten
times the distance as a move from 10 to 20 (100 points vs. 10
points). So, while the 100 point and the 10 point movement each
represent a 100% change, the 100 point movement appears to be
much greater on the chart.