Which of the following is a common issue that can make a graph misleading?

• A. The y-axis labels are missing or incomplete
• B. The vertical scale is off
• C. The data is left out
• D. The chart uses inconsistent colors

Answer: (B)

The most important idea here is that how the vertical axis is scaled can change how we perceive the differences in the data. If the y-axis doesn’t start at zero or uses nonuniform or cramped increments, the heights of bars or points won’t reflect the true proportions, making small differences look big or large differences look small. This is a common way a graph can mislead because the visual impression isn’t just about the data values—it’s about how the axis is framed. For example, showing values 4 and 5 on a chart that starts at 3 makes the difference look much more dramatic than showing them on a chart that starts at 0 with even steps.

Other issues can cause confusion, like missing or incomplete axis labels, which makes it hard to read the values; leaving data out can misrepresent the picture entirely; and using inconsistent colors can distract or confuse, but they don’t inherently distort the actual scale of the data like an off-scale y-axis can.