This Homework: Two-Group Between Subjects Design Assignment is designed to assess your understanding of the concepts and applications covered thus far in PSYC 510: Research Methods and Statistics in Psychology I. Concepts specific to this module include fundamental considerations for all parametric tests, such as threats to validity, reducing confounding variables, assumptions for parametric tests. This Homework: Two-Group Between Subjects Design Assignment also assesses your ability to conduct and interpret the independent samples t test using professional conventions. Knowledge from this module will serve as a foundation for future concepts. These topics also strengthen your ability to critically evaluate whether research is conducted in a reliable and valid manner in professional and non-professional settings.

Instructions

Be sure you have reviewed this module’s Learn section before completing this Homework: Two-Group Between Subjects Design Assignment. This Homework: Two-Group Between Subjects Design Assignment is worth 60 points. Each question is worth 3 points. Six points are awarded for mechanics/structure.

· Part I contains general concepts from this module’s Learn section.

· Part II requires use of SPSS. You will have to take screen shots and/or copy and paste from your SPSS to place answers within this file. Make sure you only insert relevant and legible images.

· Part III is the cumulative section. These may include short answer and/or use of SPSS but will review material from previous module(s).

· Directions for each subsection are provided in the top of each table (in the blue shaded areas).

· Answers should be placed where indicated (wherever there is “ANSWER”).

· Submit the file as a WORD document (.doc or .docx). Make sure the filename of your submission includes your full name, course and section.

· Example: HW7_JohnDoe_510B01

Make sure to check the Homework Grading Rubric before beginning this Homework: Two-Group Between Subjects Design Assignment.

Part I: General Concepts

These questions are based on the concepts covered in this module’s Learn section.

Answer the following questions using your own words.

1.

What are some advantages and disadvantages in the use of a posttest-only control group design versus a pretest/posttest control group design? (Must identify at least one advantage and one disadvantage per design – so four total).

ANSWER

2.

What is a confound and how is it related to internal validity?

ANSWER

3.

What is the relationship between external validity and the college sophomore problem?

ANSWER

4.

On the most recent exam in your biology class, every student earned an A. The professor claims that he must really be a good teacher for all of the students to have done so well. Given the confounds discussed this week, what alternative explanation can you offer for this result? (Don’t just list a concern– briefly provide a justification).

ANSWER

5.

A health magazine recently reported a study in which researchers claimed that women who take iron supplements have better problem-solving abilities. Further investigation revealed that they assessed problem-solving abilities in a group of women and then had the women self-report whether or not they take iron supplements. Discuss one potential threat to internal validity as it relates specifically to this study.

ANSWER

Scenario: According to some research, males have better spatial skills than do females; and according to other research, females have better reading skills than males. A student is interested in determining which gender performs better on a word-search puzzle (a puzzle in which words are hidden vertically, horizontally, and diagonally within an array of letters) since this type of puzzle involves both spatial and reading skills. A sample of males and females volunteer to participate and are given 10 minutes to work on a 50-word puzzle. The number of words correctly recognized is recorded for each subject. Use this scenario to answer the following questions.

6)

What is the independent variable? Dependent variable? What is the scale of measurement for each?

ANSWER

7)

If they reported t (25) = 1.80 and it is two-tailed, using the critical value table in your e-book, what is tcv (do NOT round). Also state whether the researcher should REJECT or FAIL TO REJECT the null hypothesis.

ANSWER

8)

Briefly describe a conceptual replication of this study. Clearly identify how it meets the definition of a conceptual replication.

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). Research Scenario: According to some research, males have better spatial skills than do females; and according to other research, females have better reading skills than males. A student is interested in determining which gender performs better on a word-search puzzle (a puzzle in which words are hidden vertically, horizontally, and diagonally within an array of letters) since this type of puzzle involves both spatial and reading skills. A sample of males and females volunteer to participate and are given 10 minutes to work on a 50-word puzzle. The number of words correctly recognized is recorded for each subject, and the resulting data are as follows: Males Females 12 15 8 12 9 11 11 18 10 13 12 14 7 17 Create your SPSS data file to answer the questions below (remember that the IV is your “grouping variable” and will be represented with numbers in SPSS and your DV will be data entered in a second column. Look at the example file from this module’s presentation if you want a visual reminder). 9) Paste the appropriate SPSS output. ANSWER 10) Paste appropriate SPSS graph. ANSWER 11) Calculate the r2 effect size given the SPSS output as shown in this module’s presentation. Show all of your work. Interpret it as “small”, “medium” or “large”. ANSWER 12) Write an APA-style Results section based on your analyses. Remember to use complete sentences, include the statistical notation, effect size, confidence interval, and include a decision about the null hypothesis. If it is significant, state how by reporting the means and standard deviations. ANSWER 13) What is the t obtained from your SPSS output? Using your table in the Appendix of your e-book, determine the critical t value for this study. Clearly identify the t obtained and the t critical values below. Describe how the critical value can be used to determine whether a t obtained value will result in a rejection of the null hypothesis (i.e. that it is significant). ANSWER tobt = tcv = Part III: Cumulative These questions can be related to anything covered thus far in the course. Research Scenario: In this fictitious scenario based on a study by Inzlicht and colleagues (2006), researchers examined whether sensitivitiy to race-based prejudice is related to self-regulation abilities in Black college students. They predicted that higher sensitivity to prejudice is related to lower self-regulation ability. Black university students completed two surveys to measure self-regulation abilities and sensitivity to race-based stigma. Both surveys used Likert-based responses; data is provided below for the 12 students. Create an SPSS file to answer the following questions. Self-Regulation Stigma Sensitivity 97 57 67 97 25 89 39 40 80 36 75 28 45 78 93 45 67 80 85 43 55 75 90 55