Math 221 Week 1 Lecture

1. Week 1 Lecture
MA 221
Statistics for Decision Making
Professor Brent Heard
Not to be copied or linked to
without my permission

2. Week 1 Lecture MA 221
• Week 1 (Homework and Graded DB)
• Week 2 (Homework, Graded DB and Lab)
• Week 3 (Homework, Graded DB and Quiz)
• Week 4 (Homework, Graded DB and Lab)
• Week 5 (Homework, Graded DB and Quiz)
• Week 6 (Homework, Graded DB and Lab)
• Week 7 (Homework, Graded DB and Quiz)
• Week 8 (Final Exam)

3. Week 1 Lecture MA 221
• Determine whether the data set is a population
or a sample. Explain your reasoning.
The salaries of each teacher in a high school.

4. Week 1 Lecture MA 221
• Determine whether the bold value is a parameter
or a statistic.
In a statewide survey on candy consumption,
72.7% of respondents between the ages of 40
and 49 reported M&M’s as a favorite candy.

5. Week 1 Lecture MA 221
• Determine whether the bold value is a parameter
or a statistic.
In a study of all teachers in a particular high
school, 98% own a cell phone.

6. Week 1 Lecture MA 221
• Determine whether the variable is qualitative or
quantitative.
Enrollment of an elementary school.

7. Week 1 Lecture MA 221
• Determine whether the variable is qualitative or
quantitative.
Colors of cars in the parking lot of an office
building.

8. Week 1 Lecture MA 221
• Determine whether the variable is qualitative or
quantitative.
Zip Codes of the students in your online class.

9. Week 1 Lecture MA 221
• What is the data set’s level of measurement?
Colors of cars in the parking lot of an office
building.
Nominal

10. Week 1 Lecture MA 221
• What is the data set’s level of measurement?
Daily low temperatures in Fahrenheit for
December 2011.
Interval

11. Week 1 Lecture MA 221
• What is the data set’s level of measurement?
Number of dogs each of your classmates have at
home.
Ratio

12. Week 1 Lecture MA 221
• What is the data set’s level of measurement?
College Football Rankings.
Ordinal

13. Week 1 Lecture MA 221
• Which method of data collection is described?
Asking every fifth student in line to enroll what
they are planning on majoring in.
Systematic because they are asking every nth or
5th student in line

14. Week 1 Lecture MA 221
• Which method of data collection is described?
Looking at all 20 entry level statistics classes at a
university and survey 2 students from each class.
Stratified because you have “20 classes” and you
are selecting a specific number from each

15. Week 1 Lecture MA 221
• Which method of data collection is described?
Looking at all 20 entry level statistics classes at a
university and surveying everyone in one of the
classes chosen at random.
Cluster because I randomly chose one of the
groups and surveyed ALL of them

16. Week 1 Lecture MA 221
• Which method of data collection is described?
Standing outside the local shopping mall and
asking people what they think of the new mall 15
miles away.
Convenience sampling because we are just asking
those that are convenient

17. Week 1 Lecture MA 221
• Which method of data collection is described?
Putting all of the first grade students names in a
hat and drawing one to get to sit next to the
teacher at lunch.
Random sampling because everyone or thing has
an equal of chance of getting selected

18. Week 1 Lecture MA 221
• Describe whether you would take a census or use
a sampling to collect data for the study described
below.
The average salary of the 75 workers at a small
business.
Census because you can easily get all 75

19. Week 1 Lecture MA 221
• Describe whether you would take a census or use
a sampling to collect data for the study described
below.
The average number of times per year the citizens
of a 250,000 population city use the library.
Sample because of the large number

20. Week 1 Lecture MA 221
• For the Data:
56 74 84 98 88 77 79 74 80 91
The stem and leaf would be:
5| 6
6|
7| 4479
8| 048
9| 18

21. Week 1 Lecture MA 221
Skewness
Think of a “Bell”
Or Perfect Think of a “Block of wood”
Mountain
“Tail” to the Left “Tail” to the Right

22. Week 1 Lecture MA 221
• Find the mean, median and mode for the
following set of data representing the number of
children a sample of 10 families have living at
home. Explain what each measure of center is in
plain language.
2 2 3 1 0 3 0 1 0 2
Mean = 1.4 Median = 1.5 Mode = 0 AND 2

23. Week 1 Lecture MA 221
• Find the range, mean, standard deviation for the
following set of data representing the number of
children a sample of 12 families have living at
home. Know what the terms mean.
2 2 3 1 0 3 0 1 0 2 4 3
Range = 4 Mean = 1.75 Standard Deviation = 1.36

24. Week 1 Lecture MA 221
• Average sales per customer at a Fast Food
Restaurant have a bell-shaped distribution with a
mean of $5.37 and standard deviation of 78
cents. Using the empirical rule, give the following
intervals.
• 68% of the values would fall between what two
values ( 5.37 - .78, 5.37+ .78)
• 95% of the values would fall between what two
values ( 5.37 - 2(.78), 5.37+ 2(.78))
• 99.7% of the values would fall between what two
values ( 5.37 – 3(.78)), 5.37+ 3(.78))

25. Week 1 Lecture MA 221
• Explain all of the values associated with a box
and whisker plot and what they mean.
Max
Min Median 3rd Quartile
1st Quartile

26. Week 1 Lecture MA 221
• Explain what a z score of zero would
mean. Then explain the difference between a
positive and a negative z score.
A z score of zero is right on top of the mean. A
negative z score is below the mean. A positive z
score is above the mean. It’s that simple.

27. About Me
I have worked in the NASA world since completing my
graduate degree in 1987.
I earned both my M.S. and B.S. in Mathematics from
Jacksonville State University in Jacksonville, Alabama. I
did Post Graduate work in Mathematics and Engineering
Management at the University of Alabama, Huntsville.
My teaching experience has included a number of colleges
in Alabama and Virginia, as well as many years with DeVry.
I am the live lecturer for all undergraduate and graduate
statistics classes at DeVry.
In my spare time I enjoy writing. My genre is observational
humor. In other words, I just enjoy finding humor in the
world and making people laugh. My stories can be found in
newspapers and at www.CranksMyTractor.com .

28. Week 1 Lecture MA 221
• I sometimes post additional helps in my
“Statcave” on Facebook
• You DO NOT have to be a Facebook person to
see these, I simply post there for convenience
and fun.
• Website: www.facebook.com/statcave