PSYC 354 PSYC354 Module 3 Homework 3 (Liberty University)
PSYC 354 Module 3 Homework 3
Homework 3
Central Tendency and Variability
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. Number all responses. Answer any written questions (such as the textbased 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 endofchapter questions.
1. The arithmetic average of a set of numbers is the _______.
2. What is an outlier?
3. Which measure describes the typical amount or distance a score deviates from the mean in any given distribution?
4. What is the mathematical relationship between variance and standard deviation?
5. For the following terms, write the equivalent mathematical symbol (letter or letters) for the sample statistic.
a. Standard deviation
b. Mean
c. Score
d. Number of participants in sample
6. These are the winning percentages for 11 baseball players for each one’s best 4year pitching performance: 0.755 0.721 0.708 0.773 0.782 0.747 0.477 0.817 0.617 0.650 0.651
a. What is the mean of the scores? (Compute this using a calculator.)
b. What is the median of these scores?
c. Compare the mean and median. Does the difference between them suggest that the data are skewed very much?
7. Recall the interactive graph from Homework 2 depicting household income and location in New York City. Based on this module/week’s reading, why do you think the author of this graph chose the median household income instead of the mean household income to describe central tendency?
Part II: SPSS Analysis
1. Green and Salkind, Lesson 21, Exercises 1, 4 Open the “Lesson 21 Exercise File 1” document (found in the course’s Assignment Instructions folder) in order to complete these exercises.
2. Green and Salkind, Lesson 21, Exercises 7–8 Open the “Lesson 21 Exercise File 2” document (found in the course’s Assignment Instructions folder) in order to complete these exercises. Note: The total attitude scores mentioned in #6 are already computed and included in the exercise file.
Part III: SPSS Data Entry and Analysis
 The following data are taken from the Bureau of Labor Statistics surveys from the years 2009–2013. They represent the average weekly pay for wage and salary earners measured at 4 different quarters each year and broken down by gender. Enter these data into a new file containing one variable for gender and one variable for salary. For the gender variable, code women as 1 and men as 2; remember to define these in Value Labels. There will be twenty “1”s and twenty “2”s (as many participants as in each group). The corresponding scores will be entered in the salary column. If you need an example, look at the setup of gender in the “Lesson 21 Practice Data File 1” document.
Women 
649 652 657 670 657 665 672 662 679 669 683 689 673 688 684 697 689 685 692 691 
Men 
823 815 812 825 819 844 810 813 830 824 829 825 827 843 832 848 865 828 875 854

a. In SPSS, compute descriptive statistics for each gender for these data. These steps, among others, are covered in this module/week’s SPSS tutorial. Remember to copy and paste output.
b. Create a boxplot describing the average overall weekly salary for each gender.
c. Based on these data, what is the mean weekly income for women?
d. What is the standard deviation of the weekly income for men?
e. If you were to conduct a statistical test to compare these two data sets (men and women), would it be more informative to compare the means of the groups or the ranges of the groups? Why?
The steps will be the same as the ones you have been practicing in Part I of the assignment; the only difference is that you are now responsible for creating the data file, as well. Remember to do the following:
a) Name and define your variables under the Variable View, then return to the Data View to enter the data; and
b) Paste all SPSS output and graphs into your homework file at the appropriate place.
Part IV: Cumulative
The BDI (Beck et al., 1961) is an instrument widely used to assess levels of depression in individuals in a variety of settings. The scores range from 0–63 (whole numbers only). A researcher administers the BDI to a sample of college students. The results appear in the table below. They are entered as 2 columns to save space (i.e., you will not need 2 columns in the SPSS file).
BDI Scores 

9 10 9 8 19 3 14 21 17 62 
15 12 10 4 10 21 23 18 17 61 
 Using SPSS, run a frequencies analysis that includes a frequency table and descriptive statistics for these scores. Include central tendency, dispersion, and distribution. Paste the output into your homework file.
 Create a graph to describe the data set. Justify why this graph is the best choice for these data.
 What is the skewness of this data set? What does this mean?
 What is the kurtosis of this data set? What does this mean?
 Based on your graph and your answers above, which measure of central tendency is most appropriate for describing this group of scores? Why?
Submit Homework 3 by 11:59 p.m. (ET) on Monday of Module/Week 3.