Sec1.1

  1. Data from a sample of citizens of a certain country yielded the following estimates of average TV viewing time per month for all the citizens. The times are in hours and minutes. (NA, not available)
Viewing method May 2008 May 2007 Change (%)
Watching TV in the home 127:31 121:05 5
Watching timeshifted TV 5:26 3:16 66
Using the internet 26:18 24:32 7
Watching video on internet 2:10 NA NA

 

Is the study descriptive or inferential?

  • Descriptive, because the statistics are used to make an inference about the population
  • Inferential, because the statistics are used to describe the sample.
  • Inferential, because the statistics are used to make an inference about the population.
  • Descriptive, because the statistics are used to describe the sample.

 

  1. Is the following study descriptive or inferential?

In a statistical magazine, average professional athletes’ salaries in three sports were compiled and compared for the years 1993 and 2003.

  Average salary ($1000)
Sport 1993 2003
A 1,053 2,307
B 1,332 3,907
C 656 1,248

Is the study descriptive or inferential?

  • Descriptive, because the statistics are a summary of the average salaries of professional athletes in three sports.
  • Inferential, because the statistics are used to make an estimate of the average salaries of all professional athletes.
  • Descriptive, because the statistics are used to make an estimate of the average salaries of all professional athletes.
  • Inferential, because the statistics are a summary of the average salaries of professional athletes in three sports.

 

  1. A recent article postulated that support for a certain scientist’s theories increases with level of education. The table shown to the right provides percentages of a certain country’s adults, by educational level, who believe that evolution is a scientific theory well supported by evidence. Complete parts A and B.

 

Education Percentage
Postgraduate education 65%
College graduate 52%
Some college education 32%
High school or less 20%

 

  1. Do you think that this study is descriptive or inferential? Explain your answer.
  • The study is descriptive because it involves percentages.
  • The study is inferential because a sample was used to make an inference about the population.
  • The study is descriptive because it is a summary of the opinions of a sample of adults.
  • The study is inferential because a sample was taken.
  1. If, in fact, the study is inferential, identify the sample and population.
  • The sample is adults who believe that evolution is a scientific theory well supported by evidence. The population is the adults who were interviewed.
  • The sample is the adults who interviewed. The population is the country’s adult population.
  • The study is descriptive.

 

  1. Determine whether the study depicts an observational study or an experiment.
  2. A study is conducted to determine if there is a relationship between colon cancer and fat consumption. Patients with colon cancer are asked about their fat consumption.
  3. A poll is conducted in which 673 women are asked about what type of car they drive.
  4. Fifty patients with diabetes are divided into two groups. One group is treated with an experimental drug. The other is not. After one year, both groups are questioned about their blood sugar levels.

 

  1. A report stated that “54% of people between the ages of 18 and 30 oppose raising taxes”. The percentage of 54% was computed from the sample data. Complete parts (a) through (d).
  • Identify the population under consideration.

The population is _____________________________________.

  • Identify the sample under consideration.

The sample is ________________________________________.

  • Is the statement in quotes descriptive or inferential? Choose the correct answer below.
  • The statement is descriptive, since it summarizes information about the sample.
  • The statement is inferential, since it draws a conclusion about the population based on a sample.
  • The statement is descriptive, since it summarizes information about the population.
  • The statement is inferential, since it draws a conclusion about the population based on the percentage who oppose raising taxes.
  • If you wanted to make it clear that the percentage of 54% was computed from sample data, how would you rephrase the statement in quotes?
  • “54% of those surveyed oppose raising taxes”
  • “54% of all people oppose raising taxes”
  • “54% of those surveyed between the ages of 18 and 39 oppose raising taxes”
  • “54% of those surveyed who oppose raising taxes are between the ages of 18 and 39”

 

sec1.2 & sec1.3

  1. Five state officials are listed to the following:

Governor (G), Secretary of State (S), Attorney General (A), Representative (R), Press Secretary (P)

  • List all 10 possible samples (without replacement) of size 3. Use the letter abbreviation for each official.
  • If a simple random sampling procedure is used to obtain a sample of three officials, what are the chances that it is the first sample on your list in part (a)? the second sample? The tenth sample?

 

  1. To estimate the percentage of defects in a recent manufacturing batch, a quality control manager at Toyota selects every 14th car that comes off the assembly line starting with the eighth until she obtains a sample of 60 cars. What type of sampling is used?

 

  1. One characteristic measured about high schools is the percent free lunch, which is the percentage of the student body that is eligible for free and reduced-price lunches. The top 100 schools, grouped according to their percent free lunch, is as follows.

 

Percent free lunch (x) Number of top 100 ranked high schools
0 45
10 18
20 12
30 7
40 18

If stratified random sampling with proportional allocation is used to select a sample of 25 high schools, how many would be selected from the stratum with a percent-free-lunch value of 40  X? (Round up to the nearest integer)

 

Sec.1.4

  1. In a study, 2439 patients took a certain drug and 1379 patients were given placebo. Identify the following:
  2. Which of the following is the treatment group?
  • The 2439 patients who took the drug
  • The 2439 patients who took placebo
  • The 1379 patients who took placebo
  • The 3818 patients who took part in the study
  • The 1379 patients who took the drug
  1. Which of the following is the control group?
  • The 1379 patients who took the drug
  • The 1379 patients who took placebo
  • The 2439 patients who took the drug
  • The 3818 patients who took part in the study
  • The 2439 patients who took placebo
  1. Which of the following is (are) the treatment(s)?
  • The administering of placebo
  • The 2439 patients who took the drug and the 1379 patients who took placebo
  • The quantity of the drug administered and the quantity of placebo administered
  • The administering of the drug and the administering of the placebo
  • The administering of the drug
  1. In a study, the effects of the mane of a male lion as a signal of quality to mates and rivals was explored. Four life-sized dummies of male lions provided a tool for testing female response to the unfamiliar lions whose manes varied by length (long or short) and color (blonde or dark). The female lions were observed to see whether they approached each of the four life-sized dummies. Complete part A through E below.
  2. Identify the experimental units. Choose the correct answer below.
  • The mane lengths
  • The male dummies
  • The female lions
  • The mane colors
  1. Identify the response variable. Choose the correct answer below.
  • Whether or not (yes or no) the mane length affected how the female lions reacted to a male dummy
  • Whether or not (yes or no) the female lions approached the same dummies.
  • Whether or not (yes or no) the female lions approached a male dummy.
  • Whether or not (yes or no) the mane color affected how the female lions reacted to a male dummy.
  1. Identify the factor(s).
  2. Identify the levels of each factor.
  3. Identify the treatments. Choose the correct answer below and fill in the answer box to complete your choice.
  • The different combinations of mane length, mane color, and number of female lions.
  • The different levels of mane length.
  • The different combinations of mane color and number of female lions
  • The    different combinations of mane length and mane color
  • The different levels of mane color
  • The different combinations of mane length and number of female lions.

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