Part I: Concepts
These questions are based on the Nolan and Heinzen reading and end-of-chapter 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 4-year 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.
David collects anxiety scores from 15 college students who visit the university health center during finals week.
1. Compute descriptive statistics on the anxiety scores. From the output, identify the following:
a. Skewness:
b. Mean:
c. Standard deviation:
d. Kurtosis:
2. Compute percentile ranks on the anxiety scores assuming that the distribution of scores is normal. What are the scores associated with the percentile ranks of 12, 27, 38, 73, and 88?
3. Compute percentile ranks on the anxiety scores, not assuming that the distribution of scores is normal. 4. Create a histogram to show the distribution of the anxiety scores. Edit the graph so that most of the normal curve is visible.
8. Create boxplots showing the distributions of the total attitude scores for the two political parties.
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 set-up of gender in the “Lesson 21 Practice Data File 1” document
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).
1. 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.
2. Create a graph to describe the data set. Justify why this graph is the best choice for these data.
3. What is the skewness of this data set? What does this mean?
4. What is the kurtosis of this data set? What does this mean?
5. Based on your graph and your answers above, which measure of central tendency is most appropriate for describing this group of scores? Why?
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