PSYC 510 HOMEWORK 8 Paired Samples t-test
Homework 8
Paired Samples t-test
When submitting this file, be sure the filename includes your full name, course and section. Example: HW8_JohnDoe_510B01
Be sure you have reviewed this module/week’s lesson and presentations along with the practice data analysis before proceeding to the homework exercises. Complete all analyses in SPSS, then copy and paste your output and graphs into your homework document file. Answer any written questions (such as the text-based questions or the APA Participants section) in the appropriate place within the same file.
All questions are worth 2 pts unless otherwise stated.
| Part I: General Concepts
These questions are based on the concepts covered in this week’s assigned readings and presentations. |
| Fill in the highlighted blanks with the best word or words. | ||
| 1) | Within-subjects designs have more statistical power because Answerbetween conditions are minimized. | |
| 2) | The formula for the degrees of freedom in a correlated groupsttest is: Answer. | |
| 3) | A counterbalancing technique to control for order effects without using all possible orders is known as Answer. | |
| 4) | If you want to ensure equivalency of groups but do not want carryover effects, you should use aAnswerdesign. | |
| 5) | If you are conducting a within subjects design with two conditions and want 30 participants in each condition, how many participants total do you need? Answer | |
| Given the mean of the difference scores is 17.0, standard deviation of the difference scores is 2.8, and there were 31 in the sample, solve for the following problems, showing all work to receive full credit: | |
| 6) Solve for the standard error of the difference scores: | |
| Work: | Answer |
| 7) Calculate the correlated-groups t test to determine the tobt. | |
| Work: | Answer |
| 8)If this is a non-directional test, what is the t cv? | |
| (No work needed) | Answer |
| Identify the statistical test that should be used to analyze the data for the following study: | |
| 9) Does a GRE prep course improve GRE scores? GRE practice test scores were compared before and after 40 students had taken a very expensive GRE prep course. | Answer |
| Given a result of t (120) = 1.95 for a one-tailed paired samples t-test, answer the following: | |
| 10) What is the sample size? | Answer |
| 11) What is the tcv? | Answer |
| 12) What is the tobt? | Answer |
| 13) What should the researcher conclude about the Ho(reject or fail to reject)? | Answer |
| Part II: SPSS Application
These questions require the use of SPSS. Remember you must submit all of your work within this word document. You will need to take a screen shot of your data view if necessary, or copy and paste your output into the spaces below. Remember to report the exact p value provided by SPSS output – simply reporting p<.05 or p>.05 is not acceptable (unless SPSS output states p=.000 – in that case you can report p<.001).
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| Research Scenario: A developmental psychologist is studying whether attachment can be improved upon by providing a parent training course. He has 10 parents who are seeking services to improve their children’s attachment to them. He uses a measure of which higher scores indicate more secure attachments to caregivers and gave it to them before and after the 4 week parent training course. The attachment scores data are presented below for Before and After the parent training course. Assume the data are normally distributed. Did the parent training course improve attachment?
Answer the following questions based on the provided scenario.
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| 14) Conduct a correlated groups t-test. Paste the appropriate SPSS output below. | |||||||||||||||||||||||
| Answer
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| 15) Use the output to calculate r2(show your work in the space provided). Interpret it (small, medium, large) based on the conventions for this effect size calculation. | |||||||||||||||||||||||
| Work: | Answer | ||||||||||||||||||||||
| 16) Paste an appropriate SPSS graph (make sure you use the procedures outlined in this week’s SPSS presentation – and don’t forget to label your y axis “Attachment”. | |||||||||||||||||||||||
| Answer
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| 17) Write an APA-style Results section based on your analyses. All homework “Results sections” should follow the examples provided in the presentations. Include the effect size if you have a statistically significant finding. Remember to include a decision about the null hypothesis, report the confidence intervals, and refer to your Figure above.3 pts
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| Answer | |||||||||||||||||||||||
| Part III: Cumulative
These questions can be related to anything covered thus far in the course.
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| In this study, participants were randomly assigned to one of two situations – “stress” or “no stress”. They were then put into their assigned fictitious situation and after an hour, were asked to provide an appetite score (Likert-rating). The following data are appetite scores (with higher indicating more of an appetite / i.e. the person is hungry) from 24 participants. Assume data meets all assumptions for a parametric test.
Using the information provided, create an SPSS data file and conduct the appropriate statistical test to determine whether there is a statistically significant difference in appetite scores between the stress and no stress groups. Answer the following questions based on your analyses.
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| 18) | What is your independent variable and its scale of measurement? | |||||||||||||||||||||||||||
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| 19) | What is your dependent variable and its scale of measurement? | |||||||||||||||||||||||||||
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| 20) | Paste the output of your statistical analysis below. 3 pts | |||||||||||||||||||||||||||
| Answer
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| 21) | Create an appropriate graph based on the data and paste it below (make sure to have axes labels and error bars). 3 pts | |||||||||||||||||||||||||||
| Answer
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| 22) | Write a brief results section in APA format, referring to the table. If relevant, provide the confidence interval and effect size. Remember to specifically state whether you reject or fail to reject the null hypothesis. 3 pts | |||||||||||||||||||||||||||
| Answer
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| Use this information to answer the following questions:
· Age at onset of dementia was determined in the general population to be m = 75.5 and s = 5.8.
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| 23) | Based on the data above, what is the z score for the age of 72? 3 pts | ||
| Answer | Work: | ||
| 24) | Based on the data you have and the z table, what percentage of people might start to show signs of dementia at or before age 72? Note: DO NOT ROUND
3 pts |
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| Answer | |||
Submit Homework 8 by 11:59 p.m. (ET) on FRIDAY of Module/Week 8. Remember to name file appropriately.
| Done! |
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