1.3.6-11 Numeric Scales Start at Zero

When users must compare aggregate quantities within a display, or within a series of displays, scaling of numeric data should begin with zero.

Additional Information:
Numerical scales generally should have zero at the bottom as the first number on a vertical scale or at the left as the first number on a horizontal scale. The exceptions to this organization would be: (1) if the numbers are used for naming categories, (2) if zero is not a plausible number on the scale, or (3) if the scale contains negative numbers. If for any reason the zero point is omitted, the display should include a clear indication of that omission, and the scales on which quantities are to be compared should be the same.