Jana Sattainathan has a couple blog posts on range dimensions. First is durations:
The data is in increments of 300 seconds going from 0 to 31536000 seconds (1 year). So, this table can be used to analyze activities that take less than 1 year. The last row’s Dimension value should be used for everything that takes over one year (or you can generate more rows based on your need).
The second is size ranges:
In the middle there, one of the bar charts is “Backup Count & Duration by Size”. As the title says, this chart helps me determine which backups are small/large and determine how many backups are in each of those “Duration” buckets. The duration bucket that I used in this case could have been easily changed from GB ranges to TB ranges. For example, I filtered the chart to check counts of backups that are over 1 TB. As one can see, I have a couple of databases that are in the 2.5 to 3 TB backup size range.
Often times, ranges are enough for analysis and that greater detail of a backup being 12.8 GB versus 12.81 GB obscures more useful information.