Statistics

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Statistics
Types

1. Descriptive statistics -graphs and averages

2. Inferential statistics
-populations and samples
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Variables
1. Qualitative
2. Quantitative
a. Discrete
b. Continuous
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4 Levels of Measurement
1. Nominal level
- data is sorted into classes
2. Ordinal level
- data is ranked
3. Interval level
- difference between values is a constant size.
4. Ratio level
- a meaningful zero point - the ratio of two
values is meaningful
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Identify the Measurement Scale
11. classification of computer makes
12. the temperature readings in Washington, DC
13. college major
14. number of traffic fatalities
15. military rank.
16. time required to complete a crossword puzzle
17. order of finish in the 2001 Indianapolis 500
18. number of people at a board of directors
meeting
19. years in which Huntington Bank stock split
20. the color of the students hair in this class
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Statistics
Types

1. Descriptive statistics -graphs and averages

2. Inferential statistics
-populations and samples
organizing and grouping into meaningful form
Frequency Distribution
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Frequency Distribution Vocabulary

1. Frequency distribution organizing and grouping
   into meaningful form
2. Classes divisions in the data
3. Class interval- The size or width of the class
4. Class frequency- The number of observations in
   each class
5. Class midpoint halfway between the upper and
   lower limits
6. Relative class frequency- Shows what percent each
   class is of the total number of observations

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Constructing Frequency Distributions
1. The class intervals should be equal
2. i H-L/k
3. General rule 5 15 classes
4. 2k rule for number of classes
5. Lower limit of 1st class should be a multiple
of the interval
6. Avoid overlapping class limits
7. Avoid open-ended classes
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Frequency Distribution
1. Number of classes or class interval
size of the class
H-L k
i gt
2. Put observations in correct class
3. Count the number in each class
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Example
1. Number of tries it took members of the last
Statistics class to pass
4 3 2 10 6 6
5 8 4 8 4
6 2 3 3 7 5
Tries Tallies Num
2 to 4
4 to 6
6 to 8
8 to 10
10 to 12
Total
i
H L k
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Statistics
1. Class frequency -observations per class
Tries Tallies Num
2 to 4
4 to 6
6 to 8
8 to 10
10 to 12
Total
2. Class midpoint -halfway between upper and
lower class limit
3. Relative Class frequency what
percent each class is of the total number
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Relative Class Frequency
Divide each class frequency by total frequency
Tries Number Rel. Freq. Calc
2 to 4 5 .2941 /
4 to 6 5 .2941 /
6 to 8 4 .2353 /
8 to 10 2 .1176 /
10 to 12 1 .0588 /
Total 17 .9999
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Histogram
frequencies marked by heights of the bars
years
6
5
4
3
2
1
1
0
7
3
5
9
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Length of Service
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Frequency Polygon
line segments connect points at midpoints
years
6
5
4
3
2
1
1
0
7
3
5
9
11
13
Length of Service
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Cumulative Frequency Distribution
line segments connect points at midpoints
years
100
15
10
5
1
0
7
3
5
9
11
Length of Service
15
Dr. Tillman is Dean of the School of Business
Socastee University. He wishes prepare to a
report showing the number of hours per week
students spend studying. He selects a random
sample of 30 students and determines the number
of hours each student studied last week.
15.0, 23.7, 19.7, 15.4, 18.3, 23.0, 14.2, 20.8,
13.5, 20.7, 17.4, 18.6, 12.9, 20.3, 13.7, 21.4,
18.3, 29.8, 17.1, 18.9, 10.3, 26.1, 15.7, 14.0,
17.8, 33.8, 23.2, 12.9, 27.1, 16.6.
Organize the data into a frequency distribution.
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H L n k
15.0, 23.7, 19.7, 15.4, 18.3, 23.0, 14.2, 20.8,
13.5, 20.7, 17.4, 18.6, 12.9, 20.3, 13.7, 21.4,
18.3, 29.8, 17.1, 18.9, 10.3, 26.1, 15.7, 14.0,
17.8, 33.8, 23.2, 12.9, 27.1, 16.6.
i
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Line graphs are typically used to show the change
or trend in a variable over time.
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(No Transcript)
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A Bar Chart can be used to depict any of the
levels of measurement (nominal, ordinal,
interval, or ratio).
Construct a bar chart for the number of
unemployed per 100,000 population for selected
cities during 2001
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(No Transcript)
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A Pie Chart is useful for displaying a relative
frequency distribution. A circle is divided
proportionally to the relative frequency and
portions of the circle are allocated for the
different groups.
A sample of 200 runners were asked to indicate
their favorite type of running shoe. Draw a pie
chart based on the following information.
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Pie Chart for Running Shoes