joeu2004 -

This is a question about the Histogram Data Analysis tool. By default,
Excel seems to apply some (unclear) heuristic for determining the number
of bins. <

Seems to be approximately from MIN(data) to MAX(data) with INT(SQRT(n))
bins.

Is there an easy way for me to force the number of bins to be N? The
operative word is "easy". <

I don't think so. I think you need to use your judgment.

I know that the tool allows me to specify a "bin range", a range of cells
that specify the lower bound of each bin. <

No, I think each bin value is the inclusive upper bound of a value range.

But that seems "hard" for me use because the range of data cells change,
based on the number of data points I want to include in the histogram. I
might (please confirm) be able to assign an array name to a data cell
range, then constuct an N-cell bin range that uses the min() and max() of
the array name. By reassigning the array name to different data cell
ranges, the bin range values should change automatically. But it would be
"easier" if the histogram tool allowed me to simply specify the number of
bins, and the tool computed the lower bound based on the data range, as I
would. I am looking for something that "easy". Since the need seems so
"obvious" and "common", I suspect I am simply failing to see how to do it.
<

I don't think it's "easy" at all. As I said, I think you need to use your
judgment. Most people find histograms easier to interpret if the bin values
are multiples of 2, 4, or 5. And most people prefer to have more bins when
the number of values in the data set is larger. An algorithm that
incorporates "nice" intervals is not trivial.

You might be interested in looking at the "Better Histogram" page at
www.treeplan.com to see a solution to a related histogram issue.

- Mike

www.mikemiddleton.com