Miscellaneous
True or False
The following question is a valid statistical question?
What is the average amount of money (cash) in a Ravenwood’s students pockets?
TRUE…the amount of money in a students pockets has many values it can take on, it can vary
The sales force for a publishing company is constantly on the road trying to sell books. As a result, each salesperson accumulates many travel-related expenses that he or she charges to a company-issued credit card. To prevent fraud, management hires an outside company to audit a sample of these expenses. For each salesperson, the auditor prints out the credit card statements for the entire year, randomly chooses one of the first 20 expenses to examine, and then examines every 20th expense from that point on. Which type of sampling method is the auditor using for each salesperson?
Systematic
You want to know the opinions of American high school teachers on the issue of establishing a national proficiency test as a prerequisite for graduation from high school. You obtain a list of all high school teachers belonging to the National Education Association (the country’s largest teachers’ union) and mail a survey to a random sample of 2500 teachers. In all, 1347 of the teachers return the survey. Of those who responded, 32% say that they favor some kind of national proficiency test.
The results may be affected by which sampling error?
Non response
Researchers were interested to know whether internal vehicle temperatures vary by outside temperatures. To evaluate this, temperature rise was measured continuously over a 60-minute period in a dark sedan on 16 different clear, sunny days with outside temperatures ranging from 72ºF to 96ºF. Is this an observational study or an experiment?
Observational Study
A study of the dietary habits of 20,000 men was conducted to find a link between high intakes of dairy products and prostate cancer. (Source: Harvard School of Public Health). What is the sample?
a)Male population in the United States
b)20,000 men
c)Dairy products
d)Prostate cancer
b) 20,000 men
To determine the effect of heat on player aggression, Coach Hester collected data on how many unsportsmanlike penalties were in a game and the temperature of the game that night. He is thinking: Hotter night, more plays?
What is the explanatory variable? What is the response variable?
Explanatory…Temperature
Response…Number of Unsportsmanlike Penalties
A television station is interested in predicting whether voters in its viewing area are in favor of federal funding for charter schools. It asks its viewers to phone in and indicate whether they support/are in favor of or are opposed to this. Of the 2241 viewers who phoned in, 1574 (70.24%) were opposed to federal funding for charter schools. Referring to this information, the viewers who phoned in are
a)A convenience sample
b)A voluntary response sample
c)The population
b) A voluntary response sample
In the design of a survey, which of the following best explains how to minimize response bias?
a)Increase sample size
b)Randomly select the sample
c)Increase the number of questions in the survey
d)Carefully word and field-test survey questions
d) Carefully word and field-test survey questions
An experimenter believes that two new exercise programs are more effective than any current exercise routines and wishes to compare the effectiveness of these two new exercise programs on physical fitness. The experimenter is trying to determine whether or not a control group, which follows neither of these new programs but continues with current exercise routines, would be beneficial. Which of the following can be said about the addition of a control group?
A) A control group would eliminate the placebo effect.
B) A control group would eliminate the need for blinding in the study.
C) A control group would allow the experimenter to determine which of the two exercise programs improves physical fitness the most.
D) A control group would allow the experimenter to determine if either of the exercise programs is more effective than current programs for physical fitness.
E) There would be no added benefit to having a control group.
D) A control group would allow the experimenter to determine if either of the exercise programs is more effective than current programs for physical fitness.
Which of the following are sampling methods that result in unbiased statistical data?
Select all that apply.
a)Systematic
b)Convenience
c)Simple Random Sample
d)Stratified
e)Voluntary Response
f)Cluster
a)Systematic
c) Simple Random Sample
d) Stratified
f) Cluster
Mrs. Wilkes wanted to determine the RHS student body’s opinion on the inventory available at the The Store. She sends a survey out to every single student at Ravenwood. Mrs. Wilkes is attempting to take a _____________ of the RHS student body.
Census
A marketing research firm wishes to determine if the adult men in Laramie, Wyoming, would be interested in a new upscale men’s clothing store. From a list of all residential address in Laramie, the firm selects a SRS of 100 and mails a brief questionnaire to each. The population of interest is
a)All adult men in Laramie, Wyoming
b)The 100 addresses to which the survey was mailed
c)The members of the marketing firm that actually conducted the survey
d)All residential addresses in Laramie, Wyoming
e)Upscale men’s clothing store
a)All adult men in Laramie, Wyoming
Respondents to a randomly distributed questionnaire answered the question, “Do you agree that nuclear weapons should never be used because they are immoral?” The study that uses the results of this questionnaire will most likely suffer from which type of bias?
Wording of Questions
A drug company wishes to test a new drug. A researcher assembles a group of volunteers and randomly assigns them to one of two groups---one to take the drug and one to take a placebo. In addition, the company wants the experiment to be double-blind. What is the meaning of double-blind in this situation?
A) The volunteers in both groups are blindfolded when they take the drug or placebo.
B) the volunteers in both groups do not know whether they are taking the drug or the placebo.
C) Neither the volunteers nor the drug company executives know which volunteers are taking the drug and which are taking the placebo.
D) Neither the volunteers nor the evaluator now which volunteers are taking the drug and which are taking the placebo.
E) as long as the subjects are randomly assigned to the two groups, there is no need to make the experiment double-blind.
D) Neither the volunteers nor the evaluator now which volunteers are taking the drug and which are taking the placebo.
Which of the following are valid statistical questions? Select all that apply.
a)How many years has Mr. Doerner been teaching?
b)What is your eye color?
c)Do you use Venmo?
d)What is RHS Class of 2024 Average ACT Score?
b) What is your eye color?
c) Do you use Venmo?
In the late 1990’s Scotland was considering independence from England. An opinion poll showed that 51% of Scots favored "independence." Another poll taken at the same time showed that only 34% favored being "separate" from England. The reason these results differ by so much is that
a. samples will usually differ just by chance due to random sampling.
b. the wording of questions has a big effect on poll results.
c. the second poll suffered from undercoverage.
d. more follow-up efforts reduced the nonresponse rate of the second poll.
b. the wording of questions has a big effect on poll results.
A researcher is interested in the cholesterol levels of adults in the city in which she lives. A free cholesterol screening program is set up in the downtown area during the lunch hour. Individuals can walk in and have their cholesterol levels determined for free. 173 people use the service, and their average cholesterol is 217.8. The sampling method is…
Voluntary Sample
A study of human development showed two types of movies to groups of children. Crackers were available in a bowl, and the investigators compared the number of crackers eaten by children watching the different kinds of movies. One kind of movie was shown at 8 AM (right after the children had breakfast) and another at 11 AM (right before the children had lunch). It was found that during the movie shown at 11 AM, more crackers were eaten during the movie show than at 8 AM. The investigators concluded that the different types of movies had an effect on appetite. The results cannot be trusted because
a)The study was not double-blind. Neither the investigators nor the children should have been aware of which movie was being shown.
b)The investigators were biased. They knew beforehand what they hoped the study would show.
c)The investigators should have used several bowls, with crackers randomly placed in each.
d)Children do not eat crackers while watching movies.
e)The time the movie was shown is a confounding variable.
e) The time the movie was shown is a confounding variable.
Can pleasant aromas help a student learn better? Two researchers had 22 people work through a pencil-and-paper maze six times, three times while wearing a floral-scented mask and three times wearing and unscented mask. The three trials for each mask closely followed one another. Testers measured the length of time it took subjects to complete each of the six trials. They reported that, on average, subjects wearing the floral-scented mask completed the maze more quickly than those wearing the unscented mask, although the difference was not statistically significant. This study is…
a)A completely randomized design
b)A randomized block design
c)A matched-pairs design
d)An observation study
c) A matched-pairs design
To gather data on a 1200-acre pine forest in Louisiana, the U.S. Forest Service laid a grid of 1410 equally spaced circular plots over a map of the forest. A ground survey visited a sample of 10% of the plots. Explain how you would use a random number generator to choose an SRS of 141 plots.
a)Number the plots from 1 to 1410. Use a random number generator to select 141 different integers from 1 to 1410. Select the corresponding 141 plots.
b)Number the plots from 1 to 1410. Use a random number generator to select 141 integers from 1 to 1410. Select the plots corresponding to those numbers.
c)Number the plots from 1 to 1410. Use a random number generator to select 141 different integers from 1 to 1500. Select the corresponding 141 plots.
a)Number the plots from 1 to 1410. Use a random number generator to select 141 different integers from 1 to 1410. Select the corresponding 141 plots.
A local tax reform group polls the residents of the school district and asks the question, “Do you think the school board should stop spending taxpayers’ money on non-essential arts programs in elementary schools?” The results of this poll are likely to
a. Underestimate support for arts programs because of undercoverage.
b. Underestimate support for arts programs because of the way the question is worded.
c. Overestimate support for arts programs because of undercoverage.
d. Overestimate support for arts programs because of the way the question is worded.
e. Accurately estimate support for arts programs.
b. Underestimate support for arts programs because of the way the question is worded.
At a local community college, five statistics classes are randomly selected out of 20 and all of the students from each class are interviewed.
Identify the sampling method used.
Cluster
A news release for a diet products company reports: "There's good news for the 65 million Americans currently on a diet." Its study showed that people who lose weight can keep it off. The sample was twenty graduates of the company's program who endorse it in commercials. The results of the study are probably
a. biased, overstating the effectiveness of the diet.
b. biased, understating the effectiveness of the diet.
c. unbiased because these are nationally recognized individuals.
d. unbiased, but they could be more accurate. A larger sample size should be used.
e. biased, but it is hard to tell whether the results will overstate or understate the effects of the diet.
a. biased, overstating the effectiveness of the diet.
A graduate student is conducting an experiment to determine whether a new activity-based method is better than the traditional lecture of teaching statistics. He found two teachers to help him in his study for one semester. Mr. Dull volunteered to continue teaching with traditional lectures and Ms. Perky agreed to try the new activity-based method. Each teacher planned to teach two sections of approximately forty students each for adequate replication. At the end of the semester, all sections would take the same final exam and their scores would be compared. Identify the explanatory and response variables.
Explanatory: the type of teaching method
Response: scores on the final exam
In order to assess the effects of exercise on reducing cholesterol, a researcher took a random sample of fifty people from a local gym who exercised regularly and another random sample of fifty people from the surrounding community who did not exercise regularly. They all reported to a clinic to have their cholesterol measured. The technician measuring the cholesterol was not aware of whether or not subjects exercised regularly. This is an…
a)Observational study
b)Single-Blind Experiment
c)Double-Blind Experiment
d)Matched-Pairs Experiment
a)Observational study