PSYC 354 Homework 5 Liberty University

Homework 5

Z-Scores

Be sure you have reviewed this module/week’s lessons and presentations along with the practice data analysis before proceeding to the homework exercises. Complete all analyses in SPSS, and then copy and paste your output and graphs into your homework document file. Number all responses. Answer any written questions (such as the text-based questions or the APA Participants section) in the appropriate place within the same file. Review the “Homework Instructions: General” document for an example of how homework assignments must look.

Part I: Concepts

These questions are based on the Nolan and Heinzen reading and end-of-chapter questions.

 1.     What are always the mean and standard deviation of the z-distribution? 

2.     Define the central limit theorem. 

3.     Fill in the blanks: A z-score is based on a distribution of _____________, while a z-statistic is based on a distribution of __________________.

4. End-of-chapter problems: Remember to show work to receive partial credit where applicable. For help working on these problems, refer to the presentation from this module/week on the normal curve and computing z-scores.

b.     In your data set, standardize the IQ scores by transforming them into z-scores under a new variable “ZIQ.” Using your data set as a reference, what z-score corresponds to a raw IQ score of 115? To a raw IQ score of 60? To a raw IQ score of 104? 

c. Based on what you have been told about IQ scores in the beginning of the problem, does this sample’s distribution seem to reflect the distribution of IQ scores in the general population? Why or why not? 

Part IV: Cumulative

1.     (Non-SPSS) A cognitive psychologist wants to find out whether playing Minecraft® affects fourth graders’ scores on a visuospatial task. He assigns 30 fourth graders to 1 of 2 groups. Group 1 plays Minecraft® for 20 minutes, then completes the visuospatial task. Group 2 completes the visuospatial task without playing Minecraft®

a.     What is the independent variable in this experiment? 

b.     What is the dependent variable? 

c.     What is the likely null hypothesis for this experiment? 

d.     What is the likely research hypothesis for this experiment?

 2.     (Non-SPSS) A clinical psychologist wants to test a new long-term treatment program for people diagnosed with bipolar disorder. She assigns 20 participants to the new treatment program and 20 participants to a standard treatment program.

a.     Why does this experiment lack a no-treatment control group? .   

b.     In words and in parameter notation (H and m), state the likely null hypothesis for this study. 

c.     In words and in parameter notation (H and m), state the likely research hypothesis for this study.   

(SPSS) A criminal psychologist wants to examine the level of narcissistic personality traits between those who are diagnosed with antisocial personality disorder (ASPD) and those who do not qualify for ASPD. She administers a measure of narcissistic personality traits where higher scores indicate higher levels of narcissism and scores range from 0–35.

Create a new SPSS data file for these scores. Your file must have 2 variables: diagnosis and score. Your diagnosis variable must be set up as a 1-column grouping variable with 2 groups (diagnosis, no diagnosis) coded numerically. This will be much like the gender variable you created in a previous module/week. For example, if you code ASPD Diagnosis as 1 and No ASPD Diagnosis as 2, then the SPSS file will appear somewhat like the following: