Which statement describes the effect of changing the y-axis scale on perceived differences?

• A. It changes the underlying data values.
• B. It exaggerates the colors used in the chart.
• C. It can make differences between data groups seem more drastic than they actually are.
• D. It has no impact on interpretation.

Answer: (C)

Changing the y-axis scale shapes how our eyes interpret differences in the data. The actual numbers don’t change, but where the axis starts and how the scale is spaced can make gaps look bigger or smaller. For example, two groups at 50 and 60 differ by 10 units, but if the axis starts at 45 and goes to 65, that same 10-unit difference can look very pronounced. If you expand the axis from 0 to 100, that 10-unit gap can seem quite small. Colors and labels stay the same, and the data hasn’t changed; only the frame of reference has shifted. This is why the statement that axis changes can make differences appear more drastic than they actually are is the best description.