Module 5 Exercises

Grand Canyon University: PSY-520: Graduate Statistics 2014

Chapter 10:
3. 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.
9. 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 non-directional hypothesis is appropriate because there is insufficient empirical basis to warrant a directional hypothesis.
b. What is the null hypothesis?
c. Using α = 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?

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 non-directional hypothesis is appropriate.
b. What is the null hypothesis?
c. Using α = 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

Chapter 12:
3. How are sampling distributions generated using the empirical sampling approach?
5. What are the assumptions underlying the use of the z test?
8. How do each of the following differ?
a. s and s
b. s² and σ²
c. µ and µ
d. σ and σ

16. How does increasing the N of an experiment affect the following?
a. Power
b. Beta
c. Alpha
d. Size of real effect

20. A set of sample scores from an experiment has an N = 30 and an  obt  = 19.
a. Can we reject the null hypothesis that the sample is a random sample from a normal population with µ = 22 and σ = 8? Use α = 0.011 tail. Assume the sample mean is in the correct direction.
b. What is the power of the experiment to detect a real effect such that µreal = 20?
c. What is the power to detect a µreal = 20 if N is increased to 100?
d. What value does N have to equal to achieve a power of 0.8000 to detect a µreal = 20? Use the nearest table value for zobt.

21. 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 non-directional 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.

25. 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.

References
Academic Web Services (n.d.). The Visual Learner – Statistics. Retrieved from: http://lc.gcumedia.com/hlt362v/the-visual-learner/the-visual-learner-v2.1.html.
Pagano, R. (2013). Understanding Statistics in the Behavioral Sciences (10th ed.). Wadsworth-Cengage Learning.

ADDITIONAL INSTRUCTIONS FOR THE CLASS

Discussion Questions (DQ)

• Initial responses to the DQ should address all components of the questions asked, include a minimum of one scholarly source, and be at least 250 words.
• Successful responses are substantive (i.e., add something new to the discussion, engage others in the discussion, well-developed idea) and include at least one scholarly source.
• One or two sentence responses, simple statements of agreement or “good post,” and responses that are off-topic will not count as substantive. Substantive responses should be at least 150 words.
• I encourage you to incorporate the readings from the week (as applicable) into your responses.

Weekly Participation

• Your initial responses to the mandatory DQ do not count toward participation and are graded separately.
• In addition to the DQ responses, you must post at least one reply to peers (or me) on three separate days, for a total of three replies.
• Participation posts do not require a scholarly source/citation (unless you cite someone else’s work).
• Part of your weekly participation includes viewing the weekly announcement and attesting to watching it in the comments. These announcements are made to ensure you understand everything that is due during the week.

APA Format and Writing Quality

• Familiarize yourself with APA format and practice using it correctly. It is used for most writing assignments for your degree. Visit the Writing Center in the Student Success Center, under the Resources tab in LoudCloud for APA paper templates, citation examples, tips, etc. Points will be deducted for poor use of APA format or absence of APA format (if required).
• Cite all sources of information! When in doubt, cite the source. Paraphrasing also requires a citation.
• I highly recommend using the APA Publication Manual, 6th edition.

Use of Direct Quotes

• I discourage overutilization of direct quotes in DQs and assignments at the Masters’ level and deduct points accordingly.
• As Masters’ level students, it is important that you be able to critically analyze and interpret information from journal articles and other resources. Simply restating someone else’s words does not demonstrate an understanding of the content or critical analysis of the content.
• It is best to paraphrase content and cite your source.

 

LopesWrite Policy

• For assignments that need to be submitted to LopesWrite, please be sure you have received your report and Similarity Index (SI) percentage BEFORE you do a “final submit” to me.
• Once you have received your report, please review it. This report will show you grammatical, punctuation, and spelling errors that can easily be fixed. Take the extra few minutes to review instead of getting counted off for these mistakes.
• Review your similarities. Did you forget to cite something? Did you not paraphrase well enough? Is your paper made up of someone else’s thoughts more than your own?
• Visit the Writing Center in the Student Success Center, under the Resources tab in LoudCloud for tips on improving your paper and SI score.

Late Policy

• The university’s policy on late assignments is 10% penalty PER DAY LATE. This also applies to late DQ replies.
• Please communicate with me if you anticipate having to submit an assignment late. I am happy to be flexible, with advance notice. We may be able to work out an extension based on extenuating circumstances.
• If you do not communicate with me before submitting an assignment late, the GCU late policy will be in effect.
• I do not accept assignments that are two or more weeks late unless we have worked out an extension.
• As per policy, no assignments are accepted after the last day of class. Any assignment submitted after midnight on the last day of class will not be accepted for grading.

Communication

• Communication is so very important. There are multiple ways to communicate with me: 
  • Questions to Instructor Forum: This is a great place to ask course content or assignment questions. If you have a question, there is a good chance one of your peers does as well. This is a public forum for the class.
  • Individual Forum: This is a private forum to ask me questions or send me messages. This will be checked at least once every 24 hours.