Probability
Confidence Intervals
Planning and Conducting a Study
Exploring Data
Definitions
100
Molly earned a score of 940 on a national achievement test. The mean test score was 850 with a standard deviation of 100. What proportion of students had a higher score than Molly?
What is .18
100
A major metropolitan newspaper randomly sampled 150 readers from their list of 100,000 subscribers. They asked whether the paper should increase its coverage of local news. Forty percent of the sample wanted more local news. What is the 95% confidence interval for the proportion of readers who would like more coverage of local news?
What is (.32,.48)
100
Which of the following statements are true? 1. Random sampling is a good way to reduce response bias. 2. To guard against bias from undercoverage, use a convenience sample. 3. Increasing the sample size tends to reduce survey bias. 4. To guard against nonresponse bias, use a mail-in survey. 5. None of the above.
What is 5
100
Each year, a national achievement test is administered to 3rd graders. The test has a mean score of 100 and a standard deviation of 15. If Jane's z-score is 1.20, what was her score on the test?
What is 118
100
Central value of a data set
What is median
200
A coin is tossed three times. What is the probability that it lands on heads exactly one time?
What is .375
200
Suppose we want to estimate the average weight of an adult male in Dekalb County, Georgia. We draw a random sample of 1,000 men from a population of 1,000,000 men and weigh them. We find that the average man in our sample weighs 180 pounds, and the standard deviation of the sample is 30 pounds. What is the 95% confidence interval?
What is (178.14, 181.86)
200
An auto analyst is conducting a satisfaction survey, sampling from a list of 10,000 new car buyers. The list includes 2,500 Ford buyers, 2,500 GM buyers, 2,500 Honda buyers, and 2,500 Toyota buyers. The analyst selects a sample of 400 car buyers, by randomly sampling 100 buyers of each brand. Is this an example of a simple random sample?
What is no
200
Suppose a researcher conducts a study to find the average height of 6th grade students. Which of the following statements are true? 1. Height is a categorical variable. 2. Height is a discrete variable. 3. In this study, the researcher will work with univariate data. 4. None of the above.
What is 3
200
An experimental procedure in which neither the subjects of the experiment nor the persons administering the experiment know the critical aspects of the experiment.
What is double blind experiment
300
A bag contains 4 white counters, 6 black counters, and 1 green counter. What is the probability of drawing a white counter or a green counter?
What is 5/11
300
Suppose a simple random sample of 150 students is drawn from a population of 3000 college students. Among sampled students, the average IQ score is 115 with a standard deviation of 10. What is the 99% confidence interval for the students' IQ score?
What is (112.9, 117.1)
300
Which of the following statements are true? 1. A sample survey is an example of an experimental study. 2. An observational study requires fewer resources than an experiment. 3. The best method for investigating causal relationships is an observational study. 4. None of the above.
What is 4
300
In the context of regression analysis, which of the following statements are true? 1. A linear transformation increases the linear relationship between variables. 2. A logarithmic model is the most effective transformation method to achieve linearity. 3. A residual plot reveals departures from linearity. 4. None of the above.
What is 3
300
A number between −1 and +1 calculated so as to represent the linear dependence of two variables or sets of data.
What is correlation coefficient
400
A company owns 400 laptops. Each laptop has an 8% probability of not working. You randomly select 20 laptops for your salespeople. What is the likelihood that 5 will be broken?
What is .0145
400
Suppose the Cartoon Network conducts a nation-wide survey to assess viewer attitudes toward Superman. Using a simple random sample, they select 400 boys and 300 girls to participate in the study. Forty percent of the boys say that Superman is their favorite character, compared to thirty percent of the girls. What is the 90% confidence interval for the true difference in attitudes toward Superman?
What is (4%, 16%)
400
Which of the following statements are true? 1. Blinding controls for the effects of confounding. 2. Randomization controls for effects of lurking variables. 3. Each factor has one treatment level. 4. None of the above.
What is 2
400
A sample consists of four observations: {1, 3, 5, 7}. What is the standard deviation?
What is 2.58
400
A symmetrical curve representing the normal distribution.
What is normal curve
500
The LMB Company manufactures tires. They claim that only .007 of LMB tires are defective. What is the probability of finding 2 defective tires in a random sample of 50 LMB tires?
What is .0428
500
The local baseball team conducts a study to find the amount spent on refreshments at the ball park. Over the course of the season they gather simple random samples of 50 men and 100 women. For men, the average expenditure was $20, with a standard deviation of $3. For women, it was $15, with a standard deviation of $2. What is the 99% confidence interval for the spending difference between men and women? Assume that the two populations are independent and normally distributed.
What is ($3.79, $6.21)
500
Which of the following statements are true? 1. A completely randomized design offers no control for lurking variables. 2. A randomized block design controls for the placebo effect. 3. In a matched pairs design, subjects within each pair receive the same treatment. 4. None of the above.
What is 4
500
Every year, 50,000 runners compete in the Peachtree Road Race. They run 10 kilometers (a little over 6 miles). The average finishing time is 55 minutes, with a standard deviation of 10 minutes. Fred and Wilma completed the race in 61 and 51 minutes, respectively. Barney and Betty had finishing times with z-scores of -0.3 and 0.7, respectively. List the runners in order, starting with the fastest runner and ending with the slowest runner.
What is Wilma, Barney, Fred, Betty
500
Type I and Type II error.
What is rejecting the null hypothesis when the null hypothesis is true and accepting the null hypothesis when the null hypothesis is false
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