# Project #48165 - Statistics

Statistic 5

1. Explain in your own words why it is important to know the possible errors we might make when rejecting or failing to reject the null hypothesis.

2. A primatologist believes that rhesus monkeys possess curiosity. She reasons that, if this is true, then they

should prefer novel stimulation to repetitive stimulation. An experiment is conducted in which 12 rhesus monkeys are randomly selected from the university colony and taught to press two bars. Pressing bar 1 always produces the same sound, whereas bar 2 produces a novel sound each time it is pressed. After learning to press the bars, the monkeys are tested for 15 minutes, during which they have free access to both bars. The number of presses on each bar during the 15 minutes is recorded. The resulting data are as follows:

Subject      Bar 1     Bar 2

1                   20          40

2                   18          25

3                    24         38

4                    14         27

5                    5           31

6                   26          21

7                   15          32

8                  29           38

9                  15           25

10                  9           18

11                25            32

12                31            28

a. What is the alternative hypothesis? In this case, assume a nondirectional hypothesis is appropriate

because there is insufficient empirical basis to warrant a directional hypothesis.

b. What is the null hypothesis?

c. Using _ _ 0.052 tail, what is your conclusion?

d. What error might you be making by your conclusion in part c?

e. To what population does your conclusion apply?

3. 13. A researcher is interested in determining whether acupuncture affects pain tolerance. An experiment is performed in which 15 students are randomly chosen from a large pool of university undergraduate volunteers. Each subject serves in two conditions. In both conditions, each subject receives a short-duration electric shock to the pulp of a tooth. The shock intensity

is set to produce a moderate level of pain to the unanesthetized subject. After the shock is terminated,

each subject rates the perceived level of pain on a scale of 0–10, with 10 being the highest level. In

the experimental condition, each subject receives the appropriate acupuncture treatment prior to receiving the shock. The control condition is made as similar to the experimental condition as possible, except a placebo treatment is given instead of acupuncture. The two conditions are run on separate days at the same time of day. The pain ratings in the accompanying table are obtained.

a. What is the alternative hypothesis? Assume a nondirectional hypothesis is appropriate.

b. What is the null hypothesis?

c. Using _ _ 0.052 tail, what is your conclusion?

d. What error might you be making by your conclusion in part c?

e. To what population does your conclusion apply?

Subject    Acupuncture   Placebo

1                4                     6

2                 2                     5

3                 1                     5

4                 5                      3

5                3                       6

6                2                       4

7                3                       7

8               2                        6

9               1                         8

10             4                         3

11             3                          7

12             4                          8

13             5                          3

14             2                          5

15              1                        4

4. How are sampling distributions generated using the empirical sampling approach?

5. What are the assumptions underlying the use of the z test?

6. How do each of the following differ?

7. How does increasing the N of an experiment affect the following?

a. Power

b. Beta

c. Alpha

d. Size of real effect

8.

9. On the basis of her newly developed technique, a student believes she can reduce the amount of time

schizophrenics spend in an institution. As director of training at a nearby institution, you agree to let her

try her method on 20 schizophrenics, randomly sampled from your institution. The mean duration that

schizophrenics stay at your institution is 85 weeks, with a standard deviation of 15 weeks. The scores are

normally distributed. The results of the experiment show that the patients treated by the student stay a

mean duration of 78 weeks, with a standard deviation of 20 weeks.

a. What is the alternative hypothesis? In this case, assume a nondirectional hypothesis is appropriate because there are insufficient theoretical and empirical bases to warrant a directional hypothesis.

b. What is the null hypothesis?

c. What do you conclude about the student’s technique?

Use α=0.052 tail.

10. A physical education professor believes that exercise

can slow the aging process. For the past 10 years, he has been conducting an exercise class

for 14 individuals who are currently 50 years old. Normally, as one ages, maximum oxygen consumption

decreases. The national norm for maximum oxygen consumption in 50-year-old individuals is

30 milliliters per kilogram per minute, with a standard deviation of 8.6. The mean of the 14 individuals

is 40 milliliters per kilogram per minute. What do you conclude? Use α = 0.051 tail. biolo

 Subject Mathematics Due By (Pacific Time) 11/19/2014 04:00 pm
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