10.1
10.2
11.1/2
11.3/4
100
What are the two conditions that need to be satisfied in order to construct a confidence interval for p1-p2?
The random and the large counts conditions
100
What do you use to calculate the standard error of the sampling distribution of p1-p2?
p-hat combined
hatp_c
100
True/False: Larger values of chi-squared arise when the difference between the observed and expected counts are larger.
True
100
Knowing the value of one variable helps us predict the value of the other variable. (answer with question)
What is an association?
200
True/False: A confidence interval for p1-p2 provides convincing evidence for a difference of proportions when the interval contains 0.
False. If 0 is contained in the interval, it is plausible that there is no difference.
200
True/False: When experimenters use volunteers as subjects, researchers should not generalize the results of an experiment beyond individuals like the ones in the experiment.
True
200
A company claims that each batch of its deluxe mixed nuts contains 52% cashews, 27% almonds, 13% macadamia nuts, and 8% Brazil nuts. To test this claim, a quality control inspector selects a random sample of 150 nuts from the latest batch. Here are the results.
What's the name of the procedure? And state the appropriate hypotheses for a test that addresses the company's claim.
Chi-squared test for goodness of fit
H0: The distribution of type of nut in this batch is the same as the claimed distribution.
Ha: The distribution of type of nut in this batch different than the same as the claimed distribution.
200
In 1912, the luxury liner Titanic struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about all adult passengers who survived and who died, by class of travel. State the name of the appropriate significance test and the hypotheses.
Chi-squared test for association
H0: Survival status and class of travel are independent for all passengers on the Titanic. (no association)
Ha: Survival status and class of travel are not independent for all passengers on the Titanic. (association)
300
The book and movie A Civil Action, tells the story of a major legal battle that took place in the small town of Woburn, Massachusetts. A town well that supplied water to East Woburn residents was contaminated by industrial chemicals. During the period that residents drank water from this well, 16 of the 414 babies born had birth defects. On the west side of Woburn, 3 of the 228 babies born had birth defects. Let p1 = the proportion of all babies born with birth defects in West Woburn and p2 = the proportion of all babies born with birth defects in East Woburn. Check if the conditions for calculating a confidence interval for p1-p2 are met.
Random? Not a random sample, the data include the whole population
LCC? 16, 398, 3 and 225 are not all ≥ 10
300
Does the order in which options are presented influence people's responses? Eric randomly assigned 100 people to one of two groups. He asked the first group, "Which southwestern restaurant chain do you like better Chipotle or Qdoba?" He asked the second group, "Which southwestern restaurant chain do you like better Qdoba or Chipotle?" In the "Chipotle first" group, 31 of the 50 people said they preferred Chipotle. In the "Qdoba first" group, 25 of the 50 people said they preferred Chipotle. State the appropriate hypotheses for performing a significance test. Be sure to define the parameter.
H0: p1 - p2 = 0, p1=p2
Ha: p1 - p2 ≠ 0, p1≠p2
p1 - p2 is the true difference in proportions of people who said they preferred Chipotle ("Chipotle first" - "Qdoba first")
300
A company claims that each batch of its deluxe mixed nuts contains 52% cashews, 27% almonds, 13% macadamia nuts, and 8% Brazil nuts. To test this claim, a quality control inspector selects a random sample of 150 nuts from the latest batch. Here are the results.
Calculate the expected counts for the appropriate test assuming the null is true. (round to nearest whole number)
Cashews: 0.52(150) = 78
Almonds: 0.27(150) = 40.5
Macadamia nuts: 0.13(150) = 19.5
Brazil: 0.08(150) = 12
300
In 1912, the luxury liner Titanic struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about all adult passengers who survived and who died, by class of travel. Check if the conditions for performing a chi-squared test for association are met.
Random? Not a random sample
Large counts? all the expects counts are greater than 5
400
A sample survey was given to separate SRSs of 500 high school students and 550 college students. Researchers want to determine whether there is a difference in the proportion of high school and college students who are employed. In all, 20.4% of the high school students and 45.1% of the college students are employed. Let p1 = the proportion of high school students who are employed and p2 = the proportion of college students who are employed. Calculate a 99% confidence interval for the difference (High school - college) in the true proportion of students who are employed. Based on the interval, is there convincing evidence that a lesser proportion of high school students are employed than college students?
-0.319 to -0.175
Yes, all of the values of the interval are negative.
400
Does the order in which options are presented influence people's responses? Eric randomly assigned 100 people to one of two groups. He asked the first group, "Which southwestern restaurant chain do you like better Chipotle or Qdoba?" He asked the second group, "Which southwestern restaurant chain do you like better Qdoba or Chipotle?" In the "Chipotle first" group, 31 of the 50 people said they preferred Chipotle. In the "Qdoba first" group, 25 of the 50 people said they preferred Chipotle. Calculate the test statistic and find the P-value.
z = 1.21
P-value = 2(0.1131) = 0.2262
400
A company claims that each batch of its deluxe mixed nuts contains 52% cashews, 27% almonds, 13% macadamia nuts, and 8% Brazil nuts. To test this claim, a quality control inspector selects a random sample of 150 nuts from the latest batch. Here are the results.
Calculate the chi-squared test statistic and find the P-value.
From Table C for df = (# of categories) - 1 = 4-1 = 3 and
X^2=6.60
P-value is between 0.05 and 0.10
400
In 1912, the luxury liner Titanic struck an iceberg and sank. Some passengers got off the ship in lifeboats, but many died. The two-way table gives information about all adult passengers who survived and who died, by class of travel. Is there convincing evidence of an association between survival status and class of travel?
Chi-squared = 55.03 + 0.03 + 26.91 + 31.80 + 0.02 + 15.55 = 129.34
df = (#rows-1)(#columns-1) = (2-1)(3-1) = 2
From table C with df = 2, P-value is essentially 0
We have convincing evidence that there is an association between survival status and class of travel.