Page 1 of 12 ENGC 6310 Assignment 1- Answers Problem 1: Determine whether the given value is a statistic or a parameter. 1. The current Palestinian Legislative Council consists of 114 men and 17 women. Answer: parameter 2. A sample of university students is selected and the average (mean) amount of money spent on transportation is 80 NIS per month. Answer: statistic 3. In a study of all 3568 school teachers in local public schools, it was found that 800 teachers have master's degree or higher. Answer: parameter Problem 2: Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most appropriate. 1. Weights of students in the fifth grade of a school. Answer: levels of measurement is interval because the data are differences but no natural zero. 2. Performance ratings of a school teacher: Excellent, good, average, or poor. Answer: levels of measurement is ordinal because the data is categories and can be arranged in order. 3. National ID numbers. Answer: levels of measurement is interval because the data are differences but no natural zero. 4. Survey responses of yes, no, and undecided about a decision made by a class professor
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Page 1 of 12
ENGC 6310
Assignment 1- Answers
Problem 1:
Determine whether the given value is a statistic or a parameter.
1. The current Palestinian Legislative Council consists of 114 men and 17 women.
Answer: parameter
2. A sample of university students is selected and the average (mean) amount of money
spent on transportation is 80 NIS per month.
Answer: statistic
3. In a study of all 3568 school teachers in local public schools, it was found that 800
teachers have master's degree or higher.
Answer: parameter
Problem 2:
Determine which of the four levels of measurement (nominal, ordinal, interval, ratio) is most
appropriate.
1. Weights of students in the fifth grade of a school.
Answer: levels of measurement is interval because the data are differences but no
natural zero.
2. Performance ratings of a school teacher: Excellent, good, average, or poor.
Answer: levels of measurement is ordinal because the data is categories and can be
arranged in order.
3. National ID numbers.
Answer: levels of measurement is interval because the data are differences but no
natural zero.
4. Survey responses of yes, no, and undecided about a decision made by a class professor
Page 2 of 12
Answer: levels of measurement is nominal because the data are categories but
cannot be arranged in order.
5. A group of students develops a scale for rating the quality of the cafeteria food, with 0
representing βneutral: not good and not bad.β Bad meals are given negative numbers and
good meals are given positive numbers, with the magnitude of the number corresponding
to the severity of badness or goodness. The first three meals are rated as 2, 4, and _5.
What is the level of measurement for such ratings? Explain your choice.
Answer: levels of measurement is ratio because the data contain a natural zero
starting point.
Problem 3:
Identify the (a) sample and (b) population. Also, determine whether the sample is likely to be
representative of the population. Provide an explanation for your answer.
1. A local journalist stands on one famous street and asks 10 adults if they feel that the current
Palestinian Legislative Council is doing a good job.
Answer:
- Population: adult persons in Palestine.
- Sample: 10 persons, the sample is not likely representing the population because
it is small.
2. In a poll of 2000 randomly selected adults run in Gaza Strip, 61% said they own a solar
system for water heating when asked whether they own such system or not.
Answer:
- Population: adult persons in Gaza Strip.
- Sample: random sample, the sample is likely representing the population because
it is a random selection.
3. A graduate student at the University of Newport conducts a research project about how
adult Americans communicate. She begins with a survey mailed to 500 of the adults that
she knows. She asks them to mail back a response to this question: βDo you prefer to use
e-mail or snail mail (the U.S. Postal Service)?β She gets back 65 responses, with 42 of
them indicating a preference for snail mail.
Page 3 of 12
Answer:
- Population: adult American's.
- Sample: 65 persons, but the sample is not likely representing the population
because it is small and not randomly selected.
4. You were hired to poll a sample of adults about the models of cars they currently own. You
decided to use people with phone numbers listed in directories as the population from
which the sample is drawn. What is wrong with using people with telephone numbers listed
in directories as the population from which the sample is drawn?
Answer:
- Population: Models of cars that adult persons own.
- Sample: people that have phone numbers, but the sample is not likely representing
the population because the sample selection criteria is not accepted since the
people selected may have not cars.
Page 4 of 12
Problem 4:
Problem 6-8 (Montgomery): Preventing fatigue crack propagation in aircraft structures is an
important element of aircraft safety. An engineering study to investigate fatigue crack in n = 9
cyclically loaded wing boxes reported the following crack lengths (in mm):