MHA 610-The standard deviation of the diameter

1. The standard deviation of the diameter at breast height, or DBH, of the slash pine tree
is less than one inch. Identify the Type I error. (Points : 1)
Fail to support the claim ? < 1 when ? < 1 is true.
Support the claim ? < 1 when ? = 1 is true.
Support the claim ? < 1 when ? = 1 is true.
Fail to support the claim ? < 1 when ? < 1 is true.
2. Biologists are investigating if their efforts to prevent erosion on the bank of a stream
have been statistically significant. For this stream, a narrow channel width is a good
indicator that erosion is not occurring. Test the claim that the mean width of ten
locations within the stream is greater than 3.7 meters. Assume that a simple random
sample has been taken, the population standard deviation is not known, and the
population is normally distributed. Use the following sample data:
3.3 3.3 3.5 4.9 3.5 4.1 4.1 5 7.3 6.2

What is the P-value associated with your test statistic? Report your answer with three
decimals, e.g., .987 . (Points : 1)

3. Scientists, researching large woody debris (LWD), surveyed the number of LWD
pieces from aerial photos taken annually for the past 35 years at two different sites.
Over the 35 years of photos examined, the first site had a mean number of LWD
pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of
1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard
deviation of 2.4. Assume a .05 significance level for testing the claim that the mean
LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also,
assume the two samples are independent simple random samples selected from
normally distributed populations, but do not assume that the population standard
deviations are equal.
Construct a 90% confidence interval for the difference between the two means. Give
your answer with two decimals, e.g., (12.34,56.78) (Points : 0.5)
4. The paired data consist of the cost of regionally advertising (in thousands of dollars)
a certain pharmaceutical drug and the number of new prescriptions written (in
thousands).
Cost
Number

9
85

2
52

3
55

4
68

2
67

5
86

9
83

10
73

Find the value of the linear correlation coefficient r . Give your answer to three decimals,
e.g., .987 . (Points : 0.5)

5. Use a .05 significance level and the observed frequencies of 70 Neonatal deaths to
test the claim that number of neonatal deaths on each day of the week is equally
likely.
Mon
10

Tues
9

Wed
5

Thurs
8

Fri
15

Sat
12

Sun
11

Determine the value of the ?2 test statistic. Give your answer to two decimals, e.g., 12.34
(Points : 0.5)

6. Using a .01 significance level, test the claim that the proportions of fear/do not fear
responses are the same for male and female dental patients.
Gender
Fear Dentistry
Do Not Fear Dentistry

Male
48
21

Female
70
32

Do you reject the null hypothesis, at the .01 significance level? Enter Y for yes (reject), N for
no (fail to reject). (Points : 0.5)

7. The table represents results from an experiment with patients afflicted in both eyes
with glaucoma. Each patient was treated in one eye with laser surgery and in the
other eye was treated with eye drops. Using a .05 significance level, apply
McNemar's test to test the following claim: The proportion of patients with no
improvement on the laser treated eye and an improvement on the drops treated eye
is the same as the proportion of patients with an improvement on the laser treated
eye and no improvement on the drops treated eye.

Eye Drop Treatment
Improvement
No Improvement
Laser Surgery
Treatment

Improvement
No Improvement

15
50

10
25

Determine the value of the ?2 test statistic. Give your answer to two decimals, e.g., 12.34 .
(Points : 0.5)

8. For a study on Type 1 diabetes, medical graduate students subdivided the United
States into four study regions (Northeast, Southeast, Southwest, and Northwest). The
students randomly selected seven patients per region and recorded the number of
times during a randomly selected month that each patient used insulin shots to
regulate blood sugar levels. Use One-Way ANOVA at a .05 significance level to test
the claim that the means from the different regions are not the same.

Mean number of times patients used insulin shots to regulate blood sugar levels

Northeast
4
3
3
4
3
2
5

Southeast
6
5
6
8
6
6
8

Southwest
4
5
6
6
7
5
4

Northwest
4
4
5
6
3
5
3

Do you reject the null hypothesis, at the .05 significance level? Enter Y for yes (reject), N for
no (fail to reject). (Points : 0.5

9. The reason we cannot use multiple t-tests to claim that four populations have the
same mean is that we increase the likelihood of a type I error. (Points : 1)
True
False
10.Use the following technology display from a Two-Way ANOVA to answer this question.
Biologists studying habitat use in Lepidopteran moths measured the number of
savannah moths found at three randomly selected prairie sites with two potential
habitat interferences (expansion of row crops and grazing). Use a .05 significance
level.

Source
Site
Habitat
Site*Habitat

Df
2
1
2

SS
.1905
304.0238
.1905

MS
.0952
304.0238
.0952

F
.0381
121.6095
.0381

P
.9627
.0000
.9627

What is the value of the F test statistic for the site effect? (Points : 0.5)