All else being equal, a study with which of the following error ranges would be the most reliable?

A.) + / - 12

B.) + / - 6

C.) + / - 3

D.) + / - 9

Answer: Option C. + / -3

Solution:

The error range is most reliable if the width of the range is smaller:

Width=w=2 Absolute value (error range)

A.) w=2 Absolute value (+/-12) = 2 (12) →w=24

B.) w=2 Absolute value (+/-6) = 2 (6) →w=12

C.) w=2 Absolute value (+/-3) = 2 (3) →w=3

D.) w=2 Absolute value (+/-9) = 2 (9) →w=18

The smallest width is in option C.

C. The most reliable would have the smallest margin of error