Assignment: research psychology

1.A sample is selected from a population with µ = 80. After a treatment is administered to the individuals, the sample mean is found to be M = 75 and the variance is s2 = 100.

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a. If the sample has n = 4 scores, then calculate the estimated standar

d error and determine whether the sample is sufficient to conclude that the treatment has a significant effect? Use a two-tailed test with alpha = 0.05

b. If the sample has n=25 scores, then calculate the estimate standard error and determine whether the sample is sufficient to conclude that the treatment has a significant effect? Use a two-tailed test with alpha = 0.05

c. Describe how increasing the size of the sample affects he stanard erro and the likelihood of rejecting null hypothesis

Assignment: research psychology

2.A researcher is testing the effect of a new cold and flu medication on mental alertness. A sample of n=9 college students is obtained and each student is given the normal dose of the medicine. Thirty minutes later, each students performance is measured on a video game that requires careful attention and quick decision making. The scores for the nine students are as follows: 6,8,10,6,7,13,5,5,3.

a. Assuming that scores for students in the regular population average u=10, are the data sufficient to conclude that the medication has a significant effect on mental performance? Test at the .05 level of significance.

b. Compute r2, the percentage of variance explained by treatment effect.

c. Write a sentence demonstrating how the outcome of the hypothesis test and the measure of effect size would be presented in a research report.

3.A researcher conducts an independent-measures study examining how the brain chemical serotonin is related to aggression. One sample of rats serves as a control group and receives a placebo that does not affect normal levels of serotonin. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. The data are as follows.

Control Low Serotonin
n = 10 n = 15
M = 14 M = 19
SS = 180.5 SS = 130.0
a. Does the drug have a significant effect on aggression? Use an alpha level of .05, two
tails.

4. An educational psychologist studies the effect of frequent testing on retention of class material. In one section of an introductory course, students are given quizzes each week. A second section of the same course receives only two tests during the semester. At the end of the semester, both sections take the same final examination. The summarized scores below frequent quizzesn=20, M=73, two exams- n=20;M=68.

Assignment: research psychology

a. If the sample variance is s2=38 and second has s2=42, do the data indicate that testing frequency has siggnificant effect on performance? Use a two tailed test at the .05 level of signifficance. (note because the two samples are the same size, the pooled variance is simply the average of the two sample variances.)

b. If the first sample variance is s2=84 and the second sample has s2=96, to tge data indicate that testing has signifficant effect? Again use a two tailed test with Alpha=.05.

c. Describe how the size of the variance effects the outcome of the hypothesis testing?

5. The following data are from an independent-measures experiment comparing two treatment conditions.

treatment 1 is 4,5,12,10,10,7 and treatment 2 is 19,11,18,10,12,14.

a. Do these data indicate a signifficant difference between the tretment at the 0.5 level of significance?

b.wWrite a sentence demonstrating how the outcome of the hypothesis test and the measure of effect size would appear in a research report.

6. One of the major advantages of a repeated-measures desing is that it removes individulal differences from the variance and therefore reduces the standard error. The follwing two sets of data demonstrate this fact. The 1st set of data represents the original results from a repeated measures study. To create the 2nd set of data we started with the original scores but increased the individual differences by adding 10points to each score for subject B, adding 20 points to each score for subject C and adding 30 points to each score for subject D. Note that this change produces a huge increase in the difference from one subject to another and a huge increase in the variability of the scores within each treatment condition

Set 1.                                                Set 2.

Subject     I          II                        Subject         I      II

A            12         14                          A            12    14

B             7         17                           B            17     27

C            11        12                           C            31     33

D            10        12                           D            40     42

M=10    M=14                                    M=25    M=29

SS14  SS=14                        SS=494 SS=414

a. Find the difference scored for each set of data and compute the mean and variance for each sample of difference scores.

b. You should find that both sets of data produce the same mean difference and the same variance for the difference scores. Explain what happend to the huge individual difference that were added to the second set of data.

Assignment: research psychology

7. A researcher would like to examine how the chemical tryptophan, contained in foods such as turkey, can affect mental alertness. A sample of n = 9 college students is obtained and each student’s performance on a familiar video game is measured before and after eating a traditional Thanksgiving dinner including roast turkey. The average score dropped by M = 14 points after the meal with SS = 1152 for the difference scores.

a. Is there is significant difference in performance before eating versus after eating? Use a two-tailed test with = .05.

b. Compute r2 to measure the size of the effect.

c. Write a sentence demonstrating how the outcome of the test and the measure of effect size would appear in a research report.

8. A researcher would like to determine if relaxation training will affect the number of headaches for chronic headache sufferers. For a week prior to training, each participant records the number of headaches suffered. Participants then receive relaxation training and for the week following training the number of headaches is again measured. The data are as follows: Before–After 6–4 5–1 3–3 3–1 6–2 2–1 4–3 4–2

a. Compute the mean and variance for a sample of different scores.

b. DO the result indicate a significant differnce? Use a two tailed test with a=.05

9. A teacher gives a third grade class of n=16 a reading skills test at the beginning of the school year. To evaluate the changes that occur during the year, students are tested again at the end of the year. Their test scores revealed an average improvement of MD=4.7 points.

a.If the variance for the difference scores is s2=144, are the results sufficient to conclude that there is significant improvement? Use a one-tailed test with a=0.05.

b. If the variane for the difference score is reduced to s2=64,are the result sufficient to conclude that there is signifficant improvement? Use a two tailed test with aplha=.05

c. Describe the effect on reducing the variance of the difference score.

These two 10 and 11 are short answers questions

10. Develop a unique example scenario where you as a researcher would analyze your data using an independent sample desing.

11. Alternatively, develop a unique example scenario where you would analyze your data using a related sample design. For this example scenario, pretend that you suspect you might have a attrition (or drop out) in between your data collection times. What could you do at the design phase to counteract this attrition

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.

Assignment: research psychology

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.

research psychology

research psychology