The heart surgeons at Augusta University know that many patients who undergo corrective heart surgery have a dangerous buildup of anxiety before their scheduled operations. They have gotten together with the Augusta University psychiatry department and started a new counseling program intended to reduce this anxiety. A test of anxiety is given to patients who know they must undergo heart surgery. Then each patient participates in a series of counseling sessions, after which they are retested. The scores before and after are shown for a simple random sample of nine patients; higher scores mean higher levels of anxiety.

Patients: 1 2 3 4 5 6 7 8 9

Before: 121 93 105 115 130 98 142 118 125

After: 76 93 64 117 82 80 79 67 89

Test the hypothesis that the counseling sessions reduce anxiety; use a significance level a= 0.01 . Assume that both before and after figures are from a normal distributed population. [HINT: Your claim and hypothesis should be about _d , the mean of the differences between corresponding values.]

[ZTest ] or [TTest] or [2-SampZTest ] or [2-SampTTest] ? (circle one)

: _{1 or} Sx₁:x₁: n₁: ₂ or Sx₂: x_2: n₂:

(Circle the original claim) H0: Ha: 0:

One-Sided Left One Sided Right Two Sided (circle one)?

Test statistic: z or t

Critical Value(s) (based on or a/2 ):

Graph (sketch):

P-value:

Conclusions? (Circle one): Reject H0Fail to Reject H0

Interpretation?