NULL values in charts/visualizations
4 Oct 2012 - 2:06pm
3 replies
1847 reads
Brett Christenson
2008
Anyone know of standard conventions for displaying NULL values in visualizations like scatter plots? I am working to define this behavior for Scatter (bubble), Heat Grids and Geo Mapping visualizations but I cannot find any resources to help identify best practices. I was thinking that it would be good to indicate NULL because it may be an issue with getting data rather than no data value or if the values was actually zero. Example - a Null value for the size by or color by value does not get returned for a point on a scatter chart. Some of the graphing tools I have played with will not show that point at all if the value is NULL.
Any advice is greatly appreciated.
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The standard convention is not to show them at all, I'd say.
While I don't have any actual experience in this area, as a former electo-mechanical engineer, it has been my experience that all data is pertinent, and could be singularly important, to the subject area being charted.
Since null litterally means un-known, not just blank, you can't really plot it on a graph. I'd imagine the best you could do is include the information in a legend or some other ancillary data display.