Answer:
Step-by-step explanation:
researchers often measure individuals before and after treatment, and record the amount of difference between the two scores.
If the differences average around zero, it is an indication that the treatment has no effect.
However, if the differences are consistently positive (or consistently negative), it suggests that the treatment does have an effect.
A positive score indicates more pain before treatment than after.
a. The mean of the sample for n = 20 scores is
+4, +5, +2, 0, +7, +4, +3, +3, +2, -2, +1, +6, 0, +4, +7, -1, +3, +5, +4, +2
4 + 5 + 2 + 0 + 7 + 4 + 3 + 3 + 2 + (-2) + 1 + 6 + 0 + 4 + (-1) + 3 + 5 + 4 + 2
= 55-3 / 20
= 52/20 = +2.6
b. An average of +2.6 was estimated thus, it appears the treatment has an effect as a positive sign indicates more pain before treatment than after.