Wouldn't it be more effective to plot two % change series? That would make
the impact obvious even with a single y-axis.

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article . com,
says...
To explain the issue by way of example: revenues are declining over
time more quickly than # of customers and that should be apparent by
looking at a 2-line graph which plots revenues and customers over time.
The revenues (in milllions) and customers (in thousands) are plotted
against two different y-axes. The downward slope of revenues should be
steeper than the downward slope of customers. But, by default Excel
chooses a scale to fill the most space and this visually misrepresents
the facts. It looks like decline in revenues is proportional to
decline in customers.

QUESTION: How to calculate the interval, maximum and minimum for the
second y-axis to show the actual relationship between revenues and
customers.

Thank you!

Moshe