How do you handle long charts that span multiple pages?

Question

I need to print several bar charts to PDF for some reporting requirements. One the of the issues I am certain to encounter is how to handle the display of very long charts that span multiple pages in the PDF. Some of the charts contain up to 500 records. There is even one case that would show nearly 3000 records!

When I scale the chart down to fit on a single 8.5" x 11" page the bars and labels on the charts are no longer readable. This is also how MS Excel addresses this scenario; it experiences the same problem.

However simply continuing the chart on subsequent pages results in a jarring experience at the page break and your x-axis might be located several pages down. This makes it terribly difficult to know what you are looking at.

Several solutions have been proposed:

1. Split the chart into multiple charts to be displayed sequentially in the report
2. Reduce the size of the dataset to only the top N records so as to fit on a single page
3. Replace the chart with a more compact form such as a table with multiple columns and numeric values.

Option 1 could make it more difficult to disseminate the proper information from the chart as you have to visually scan multiple disjointed datasets.

Option 2 could cause situations where important information was truncated. Perhaps all 200 records needed to be displayed.

Option 3 could work though it could suffer the same multi-page issues as with the chart (though it would likely be reduced in severity). Additionally it could be harder to visually scan for relative differences between one record and another.

How would you handle long charts that span multiple pages? Is there a standard or accepted way for addressing this scenario?

EDIT 2011-12-27 It has been proposed that we may need re-visit and adjust the requirements as there may not be value in a chart that spans multiple pages. It could simply be too difficult to interpret no matter how we format the chart across multiple pages.

Answer 1

I have thought something about this, because it is a major problem. I think there are two responses to this. Firstly, the requirements need to be changed, because charts of this size are difficult to interpret, so it is worth some investigation into what is actually needed.

The other approach, is to print these on something larger - like an A0 printer. If these sort of charts are needed at this scale, then a specialised printer is worth while. If not, the requirements is probably not that important.

Answer 2

How about print out the header of the chart on each page with a text Displaying 50-100 etc. That way it's easier to follow. You could also add vertical zebra stripes which also makes it easier to follow. And add a page break at the beginning of every chart. Option 2 doesn't quit solve your initial task - the reporting thing. And option 3 might also be harder to interpret.