Practice: Week One

 Complete both Part A and Part B below.

Part A

Some questions in Part A require that you access data from Statistics for People Who (Think They) Hate Statistics. This data is available on the student website under the

Student Test Resources link. Practice:

1. By hand, compute the mean, median, and mode for the following set of 40 reading scores:

SUMMARY

31324342
24342544
23432436
25412328
14212417
25234421
13262332
12261442
14315212
23423234

2. Compute the means for the following set of scores saved as Ch. 2 Data Set 3 using IBM®SPSS® software. Print out a copy of the output.

Hospital size (number of beds)Infection rate (pier 1,000 admissions)
2341.7
2142.4
1653.1
4365.6
4324.9
3425.3
2765.6
1871.2
5123.3
5534.1

3. You are the manager of a fast food store. Part of your job is to report which special is selling best to the boss at the end of each day. Use your knowledge of descriptive statistics and write one paragraph to let the boss know what happened today. Use the following data. Do not use IBM®SPSS®software to compute the statistics needed; rather, do it by hand. Include a copy of your work.

Special numberSoldCost
Huge Burger20$2.95
Baby Burger18$1.49
Chicken Littles25$3.50
Porker Burger19$2.95
Yummy Burger17$1.99
Coney Dog20$1.99
Total specials sold119 

 4. Suppose you are working with a data set that has some different (much larger or much smaller than the rest of the data) scores. What measure of central tendency would you use and why?

5. For the following set of scores, compute the range, the unbiased and the biased standard deviations, and the variance. Do the exercise by hand.

31, 42, 35, 55, 54, 34, 25, 44, 35 

Why is the unbiased estimate greater than the biased estimate? 

6. Use IBM®SPSS®software to compute all the descriptive statistics for the

following set of three test scores over the course of a semester. Which test had the highest average score? Which test had the smallest amount of variability?

Test 1Test 2Test 3
505049
484947
515151
464655
494855
485345
494947
495245
504846
505553

 7. This practice problem uses the data contained in the file named Ch. 3 Data Set 3.

 There are two variables in this data set. 

VariableDefinition
HeightHeight in inches
WeightWeight in pounds

Using IBM®SPSS®software, compute all of the measures of variability you can for height and weight.

 8. Review the following frequency distribution. Create a histogram either by hand or by using some other application such as a Microsoft®Excel®document.Practice –

Week One 

Class intervalFrequency
90–10012
80–8914
70–7920
60–6924
50–5928
40–4929
30–3921
20–2915
10–1917
0–912

9. A third-grade teacher is looking to improve her students’ level of engagement during group discussions and instruction. She keeps track of each of the 15 third

graders’ number of responses every day for 1 week. This information is available in Ch. 4 Data Set 2. Use IBM®SPSS®software to create a bar chart (one bar for each day).

10. Identify whether these distributions are negatively skewed, positively skewed, or not skewed at all, and why.

 a. This talented group of athletes scored very high on the vertical jump task.

b. On this incredibly crummy test, everyone received the same score.

c. On the most difficult spelling test of the year, the third graders wept as the scores were delivered.

11. For each of the following, indicate whether you would use a pie, line, or bar chart, and why.

a. The proportion of freshmen, sophomores, juniors, and seniors in a particular university

b. Change in GPA over four semesters

c. Number of applicants for four different jobs

 d. Reaction time to different stimuli

 e. Number of scores in each of 10 categories 

From Salkind (2011). Copyright © 2012 SAGE. All Rights Reserved. Adapted With Permission.

Part B 

Complete the questions below. Be specific and provide examples when relevant.

Cite any sources consistent with APA guidelines.

QuestionAnswer
Salkind (2011) describes statistics as a “set of tools” (p. 18). How doDo behavioral scientists use those tools? 
How would you use descriptive statistics to report the effectiveness of a baseball team? How would you use inferential statistics to report the effectiveness of a baseball team? In this example, what is the sample and what is the population? 
What does a measure of central tendency tell us about a data set? Identify the three common measures of central tendency used in descriptive statistics and give anexample of each. How do you calculate them? 
What is variability in a data set? Identify three measures of variability used in descriptive statistics, explain 
how to calculate each, and give an example of each.