Essay about Ch 01 Presentation 3

Submitted By loveangelmusic
Words: 796
Pages: 4

Chapter 1
Displaying the order in a group of numbers using tables and graphs

Practice Problem
A particular block in a suburban

neighborhood has 20 households. The number of children in these households is as follows:
2, 4, 2, 1, 0, 3, 6, 0, 1, 1, 2, 3, 2, 0, 1, 2, 1,
0, 2, 2
Make (a) a frequency table, (b) a group frequency table, and (c) a histogram.
Then, (d) describe the general shape of the distribution (skew and modality BOTH!).

Frequency Table
# of Children
0
1
2
3
4
5
6
7

Frequency

Frequency Table
# of Children

Frequency

0

4

1

5

2

7

3

2

4

1

5

0

6

1

7

0

Frequency Table
Remember: Frequency Tables should go to

zero &/or include all possible numbers; NO
MISSING NUMBERS IN SERIES!

Group Frequency Tables
# of Children
0-2
3-5
6-8

Frequency

Group Frequency Tables
# of Children

Frequency

0-2

16

3-5

3

6-8

1

Group Frequency Tables
Grouped Frequency Tables must go to

zero &/or have equal intervals!
This may mean add an additional number or

two for the last group to be equal
Standard size is 3-5 numbers

Histogram
Histogram
9
8
7
6
5
4
3
2
1
0

0

1

2

3

4

5

6

7

Histogram
Histogram
8
7
6
5
Axis Title 4
3
2
1
0

0

1

2

3

4

Axis Title

5

6

7

Histograms
Put all possible values (x’s) along the

bottom of the page, left to right, lowest to highest Make a scale of frequencies along the left edge from 0 to highest frequency
Make a bar above each value for a histogram Histogram bars must be touching (except

nominal data)

Skew & Modality
Determine the if there is a skew, and if so

which direction.
Determine the modality of the distribution.

Skew & Modality
(d) Unimodal, positively skewed (or skewed

to the right).

Shapes of frequency distributions Modality
Unimodal: one main high point
Bimodal: 2 fairly equal high points
Multimodal: 2 or more high points
Rectangular: values of all about the same

frequency
Normality
Symmetrical
Skewed distribution
 Can be skewed to the right (positive) or left (negative)
 Skew is important – be sure you understand how to identify it

SPSS Fun Time!
Assume that these are employment test and performance scores for 15 accountants in a large accounting firm. These people were all hired 1 year ago. During the hiring process, they were given an Accounting Aptitude Test (scored from 0100), an Interview (which was scored from
1-poor to 10excellent candidate), and put through a 2-hour Accounting
Simulation, where they encountered real-life accounting dilemmas for which they were to suggest solutions. The number of Errors they made in the simulation (0-excellent to
5-poor) were recorded. After being on the job for 1 year, their performance was rated by their supervisor (scored from
1-very poor to 10-outstanding). It was hoped that the 3 employment “tests” would predict the applicants’…