STAT 216 Section 6 Quiz 4
Sept. 25, 2008
.
Name
1. TRUE or FALSE: The correlation coefficient of r = 0.65 indicates a stronger linear association between x and y than would r = −0.85.
2. TRUE or FALSE: The correlation coefficient measures only the strength of the linear relationship between the variables x and y.
Fstop
5
10 15 20 25 30
70
50
60
waiting
80
90
3. Describe the relationships shown in the following plots. The first shows “duration of eruption”
times on the x axis and “Waiting time to next eruption” on the y axis for the Old Faithful
geyser. The second shows the relationship between aperture opening (f-stop) and shutter
speed on an automatic exposure camera.
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Eruption Time
A. Form:
0.00
0.02
0.04
0.06
0.08
0.10
0.12
shutterSpeed
B. Form:
Circle one in each group:
A. Direction: Negative, Positive, or Neither
B. Direction: Negative, Positive, or Neither
A. Strength: Weak, Moderate, or Strong
B. Strength: Weak, Moderate, or Strong
4. Three different treatments were used on cocaine addicts to try to prevent relapse.
Treatment
Outcome: Desipramine Lithium Placebo Total
Relapsed
10
18
20
48
Recovered
14
6
4
24
Total
24
24
24
72
(a) Overall, What is the frequency distribution of Outcome?
(b) Which treatment had the highest recovery rate? (Show the numbers you are comparing.)