Descriptive Statistics: SPSS

Unit 1 Homework: Summarizing and Describing Data
This homework requires both SPSS and your calculator. There are very specific and helpful guidelines for doing this type of homework located in the Graphing Tutorial in Unit 1. Submit only one file for the entire homework into the gradebook. Either create text boxes in SPSS and type in your explanations and answers there, OR, do your work in Word, and cut and paste graphs and tables from SPSS into that document. APA format is required for figure and table captions. Remember that you must show your work to receive full credit.

In SPSS, create a database from the information in Table 1 (pg. 3) found at the end of this document. Use that information to answer questions 1 through3.

1. For the variable Math 201:
a. Create the appropriate graph (5 pts)
b. Create the appropriate descriptive statistics (5 pts)
c. What is the most appropriate descriptive statistic? Include the justification for your choices (5 pts)
d. Write out how you would explain this information to someone who had not had a course in statistics (5 pts).

2. For the variable Math Test:
a. Create the appropriate graph (5 pts)
b. Create the appropriate descriptive statistics (2.5 pts)
c. What is the most appropriate descriptive statistic? Include your justification for your choices. (2.5)
d. We know from experience that scores in the middle 50% of the distribution generally do well in our course in statistics. What scores would be the cutoffs for this range? (5 pts.)
e. Students who score below the 30th percentile on this test are referred to the Tutoring Center. How many should be referred?
(5 pts.)

3. For the variable Stat grade:
a. Create the appropriate graph (5 pts)
b. Create the appropriate descriptive statistics (2.5 pts)
c. What is the most appropriate descriptive statistic? Provide justification for your choices. (2.5)
d. What is the probability of finding a score of 90 or better? (5 pts.)
e. What scores mark the most deviant 10%? (5 pts.)

4. Reading readiness of preschoolers from an impoverished neighborhood (n = 20) was measured using a standardized test. Nationally, the mean on this test for preschoolers is 30.9, with s = 2.08.

a. Children below the 30th percentile are in need of special assistance prior to attending school. What score would indicate these children? (5 pts.)
b. What percentage of children score between 25 and 28.5? (5 pts.)
c. How many children would we expect to find with scores between 28 and 31.5? (5 pts.)
d. Children in the top 25% are considered accelerated readers and qualify for different placement in school. What score would mark the cutoff for such placement? (5 pts.)

5. Age at onset of dementia was determined for a sample of adults between the ages of 60 and 75. For 15 subjects, the results were Σx = 1008, and Σx2 =67878. Use this information to answer the following:.
a. What is the mean and s for this data? (5 pts.)
b. What is the percentile rank for an individual who shows dementia at age 62? (5 pts)
c. If we consider +/-1z to be the normal range of onset, what ages correspond to this? (5 pts.)
d. What ages identify the most deviant 20%? (5 pts.)

Table 1.

Student Database
ID # Gender GPA Math
201 Math
Test Stat
Grade
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Male
Male
Female
Female
Female
Male
Female
Female
Female
Female
Male
Male
Female
Female
Female
Female
Female
Female
Male
Female
Female
Female
Male
Male
Female
3.23
3.10
3.75
2.32
2.79
2.13
2.64
2.91
2.27
2.53
3.32
3.73
3.24
3.01
2.94
2.80
2.55
3.23
2.94
3.79
3.65
2.15
3.44
2.26
2.95
No
Yes
Yes
No
No
No
No
No
Yes
No
Yes
Yes
Yes
Yes
No
No
No
No
No
Yes
Yes
No
No
No
No
17
27
35
25
28
18
15
29
38
17
35
32
28
22
18
25
24
40
28
38
35
20
36
27
29 78
85
93
74
76
62
58
78
90
60
93
94
90
79
74
72
70
78
73
94
93
62
68
60
60

Description of Database
ID# Student identification number
Gender: 1 = male, 2 = female
GPA: Overall college grade point average
Math 201: Have you taken Math 201? 1 = No, 2 = Yes
Math Test: Score on a test of Math Skills
Stat Grade: Grade in introductory statistics course
A = 92 to 100
B = 82 to 91
C = 72 to 81
D = 62 to 71
F = 61 and below

See attached file.