At a college there are 120 freshmen, 90 sophomores, 110 juniors, and 80 seniors.
A school administrator selects a simple random sample of 12 of the freshmen, a simple random sample of 9 of the sophomores, a simple random sample of 11 of the juniors, and a simple random sample of 8 of the seniors. She then interviews all the students selected. Identify the type of sampling used in this example.
A) Stratified sampling B) Simple random sampling
C) Systematic random sampling D) Cluster sampling
Q. 2An education researcher randomly selects 38 schools from one school district and interviews all the teachers at each of the 38 schools. Identify the type of sampling used in this example.
A) Simple random sampling B) Systematic random sampling
C) Stratified sampling D) Cluster sampling
Q. 3The peak shopping time at home improvement store is between 8:00am-11:00 am on Saturday mornings. Management at the home improvement store randomly selected 180 customers last Saturday morning and decided to observe their shopping habits.
They recorded the number of items that each of the customers purchased as well as the total time the customers spent in the store. Identify the types of variables recorded by the home improvement store.
A) number of items - continuous; total time - continuous
B) number of items - continuous; total time - discrete
C) number of items - discrete; total time - continuous
D) number of items - discrete; total time - discrete
Q. 4From a group of 496 students, every 49th student starting with the 3rd student is selected. Identify the type of sampling used in this example.
A) Cluster sampling B) Simple random sampling
C) Stratified sampling D) Systematic random sampling
Q. 5Suppose that you want to perform a hypothesis test based on independent simple random samples to compare the means of two populations.
Further suppose that either the variable under consideration is normally distributed on each of the two populations or the sample sizes are large. True or false? If the population standard deviations are quite different, then using the pooled t-test can result in a significantly smaller Type I error probability than the one specified.
A) True B) False
Q. 6A college lecturer has devised a new method of teaching a particular mathematical concept and wishes to try out this teaching method on a representative sample of his students.
There are 76 students in his class and he wishes to obtain a simple random sample of 25 of them. Describe a method he could use to obtain the sample.
Q. 7A study was conducted to determine if listening to heavy metal music affects critical thinking. To test the claim, 136 subjects were randomly assigned to two groups. Both groups were administered a basic math skills exam.
The first group took the exam while heavy metal music was piped into the exam room, while the second group took the exam in a silent room. The mean exam score for the first group was 77, and the mean exam score for the second group was 91. The researchers concluded that heavy metal music negatively affects critical thinking. Identify (a) the research objective, (b) the sample, (c) the descriptive statistics, and (d) the conclusions made in the study.
Q. 8A store manager wishes to determine whether his customers would be prepared to pay a little extra for organic produce. He uses a random number table to choose 50 random numbers between 1 and 200.
He stands outside the store on a Monday morning between 9:00 a.m. and 12:00 noon and interviews the people corresponding to the random numbers. For example random number 82 would correspond to the 82nd person to arrive. Do you think that the sample obtained in this way will be representative of all the store's customers?
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