Measurement Scales (5 of 6)

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	No Distraction	Distraction
5-yr 10-yr	6 12	3 8

It looks as though the 10-year olds are more distractible since distraction cost them 4 points but only cost the 5-year olds 3 points. However, it might be that a change from 3 to 6 represents a larger difference than a change from 8 to 12. Consider that the performance of 5-year olds dropped 50% from distraction but the performance of 10-year olds dropped only 33%.

Which age group is "really" more distractible? Unfortunately, there is no clearly right or wrong answer. If proportional change is considered, then 5-year olds are more distractible; if the amount of change is considered then 10-year olds are more distractible. Keep in mind that statistical conclusions are not affected by the choice of measurement scale even though the all-important interpretation of these conclusions can be.