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Could someone recommend the best standard approach to labeling graduated data ranges?

I was thinking of the following but would like to know if this is industry standard:

Less than 0
>0 - 100
>100 - 200
>200 - 300

instead of

Less than 0
0.01 - 100
100.01 - 200
200.01 - 300

Currently programs such as QGIS default to:

...
0 - 100
100 - 200
200 - 300

Apologies if this is a really simple question but I just can't seem to decide what's best and haven't been able to find any material online.

closed as primarily opinion-based by Vince, whyzar, Dan C, PolyGeo Feb 20 at 0:54

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

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    This is a question about best practices in map legends and data presentation. I disagree with closing it as "primarily opinion-based." – csk Feb 20 at 17:39
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I don't think there's any "industry standard" or "best practice" about this, which makes this an opinion-based question. So here's my opinion. I've summarized a few different options, and their pros and cons.

"Greater than" symbols

Less than 0
>0 - 100
>100 - 200
>200 - 300
  • Pro: Concise.
  • Con: May be confusing at first glance. The > symbol is used for other types of formatting, eg as a bullet point, so people may not even realize that it's supposed to mean anything.

Decimal points

Less than 0
0.01 - 100
100.01 - 200
200.01 - 300

Adding a decimal point makes an implicit statement about data precision. To be perfectly correct, use as many decimal places as the data.

Less than 0
0.0000000000000001 - 100
100.0000000000000001 - 200
200.0000000000000001 - 300
  • Pro: Immediately understandable.
  • Con: Takes up a lot of space and/or implies an incorrect level of precision.

Overlapping integer ranges with an explanatory note

Add a note at the bottom that indicates that the beginning of each ranges is exclusive, and the end of each range is inclusive. Most people won't notice or care that the ranges apparently overlap. For the few people who do, there's a note at the bottom of the legend (or page). One note at the bottom of the page is will cover multiple data sets. Here's an example, but there's definitely room for improvement on the wording.

Less than 0
0 - 100
100 - 200
200 - 300
...
Note: Values that fall on the division between ranges are included in the lower range, eg 100 falls into the 0-100 range, not 100-200.
  • Pro: Easy to read. Efficient use of space, especially with multiple data sets.
  • Con: Will temporarily confuse anyone who notices that the ranges overlap; forces people to search for information.

Set builder notation

Put each range in brackets/parentheses. A square bracket indicates that end of the range is inclusive; a parenthesis indicates that end of the range is exclusive. Most people learned this notation in grade school mathematics, but forgot it immediately. Even people who remember it, may not remember which of bracket/parenthesis indicates inclusive vs exclusive.

More details on set builder notation are available here and here.

Less than 0
[0, 100)
[100, 200)
[200, 300)
Note: A square bracket indicates that end of the range is inclusive; a parenthesis indicates that end of the range is exclusive. For example, the range [0, 100) includes 0 and excludes 100.
  • Pro: Unambiguous.
  • Con: Requires an explanatory note unless your target audience is mathematicians.
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    The problem with using explicit floating-point values is the discontinuous imposition on a continuous range. What if thete's a value of 100.005 or 100.000001? Now your range statement is making an assertion about data precision, possibly one you did not intend to make. – Vince Feb 19 at 18:43
  • @Vince, that's an excellent point. To be perfectly precise, the legend value should have as many decimal places as the data. With high data precision that would lead to a very wide legend. 0.00000000000001 - 100 – csk Feb 19 at 18:57
  • This is my concern - totally agree with the points you are making, however presenting high precision data in a key for example can quickly clog up your presentable space. – AWGIS Feb 20 at 10:11
  • @csk I like your bottom idea of adding a note. – AWGIS Feb 20 at 10:12

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