7001ENG - Research Methods for Engineers

Task:

1) Explain the differences between a sample and a population. Why are samples used in statistics?

2) Identify the population, sample and the variable of interest in each of the following situations.
(a) To learn about starting salaries for engineers graduating from Griffith University, twenty engineering graduates are asked to report their starting salary.
(b) Fifty computer memory chips were selected from the six thousand manufactured that day. The fifty computer memory chips were tested and 5 were found to be defective.

3) A study by health economists at the University of Southern California indicated that Alzheimer's disease cost the USA $82.7 billion a year in medical expenses and lost
productivity.
a. What is the population? b. What is the variable of interest?
c. What is the parameter? d. What is the statistic?

4) Does the statement reference a population (a complete collection of observations) or a sample (any smaller collection of actual observations from a population)?
(a) A 2008 survey by the University of Queensland found that eight percent of Australians thought that they had seen a UFO.
(b) Records maintained by the Gold Coast City Council show that nine parcels of land in Coomera are owned by individuals named John Smith.
(c) Research by Monash University indicates that drinking by university students contributes to an  estimated 100,000 injuries each year.

5) Determine which part in the following statement is descriptive in nature and which is inferential:
“A survey showed that 99% of all big and tall travellers dislike cramped airline seating the most; therefore, 99% of the 10,000 King-Size Co. customers will dislike cramped airline seating the most”.

6) Does the statements below typify descriptive statistics (because it describes sets of actual observations) or inferential statistics (because it generalizes beyond collections of actual observations)?
(a) As of 2009, the actress Amy Adams had received a total of two academy award (Oscar) nominations.
(b) Australian adults are nearly 10 kg heavier now than they were in 1960.
(c) In 2013, the population of Australia was 23.13 million residents.
(d) Drinking decaffeinated coffee can raise cholesterol levels by 7%.
(e) Expenditures in the cable industry were $5.66 billion in 1996.
(f) Nine out of ten on-the-job fatalities are men.

7) What type of data are referenced in the underlined portion of the statement—qualitative (a single observation is a word, letter, or numerical code that represents a category), or
quantitative (a single observation is a number that represents an amount or count)?
(a) In 2015, the membership of Engineers Australia was comprised of 48.6% civil engineers and 10.0% mechanical engineers.
(b) In 2015, mobile phone users in Australia sent 25.4 billion text messages.
(c) The winner of the 2009 X-Games Skate Big Air competition was Jake Brown, who finished with a score of 94.00.

8) Classify each variable as qualitative or quantitative.
(a) Number of bicycles sold in 1 year by a large sporting goods store.
(b) Times it takes to cut down a lawn.
(c) Capacity in cubic meters of six truck beds.
(d) Classification of children in a day-care center (infant, toddler, preschool).
(e) Weights of fish caught in Sunshine Coast.
(f) Marital status of faculty members in a large university.
(g) Postcode of residents of the Gold Coast.
(h) Jersey number of all rugby players in Australia.

9) Classify each variable as quantitative discrete or quantitative continuous.
(a) Number of doughnuts sold each day by a doughnut store.
(b) Water temperature of six swimming pools on the Gold Coast on a given day.
(c) Weights of cats in a pet shelter.
(d) Lifetime (in hours) of 12 flashlight batteries.
(e) Number of DVDs rented each day by a video store.
(f) Capacity (in hm3) of four reservoirs in Queensland.

10) Identify each study as being either observational or experimental.
a. Subjects were randomly assigned to two groups, and one group was given an herb and the  other group a placebo. After six months, the numbers of respiratory tract infections each  group had were compared.
b. A researcher stood at each busy intersection to see if the color of an automobile that a  person drives is related to running red lights.
c. A researcher finds that people who are more hostile have higher total cholesterol levels than those who are less hostile.
d. Subjects are randomly assigned to four groups. Each group is placed on one of four special diets-a low-fat diet, a high-fish diet, a combination of low-fat diet and high-fish diet, and a regular diet. After 6 months, the blood pressures of the groups are compared to see if diet has any effect on blood pressure.