Chapter 3 What Do Samples Tell Us?

From Sample to Population 1 A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge. Identify the parameter. A. 1,000,000 batteries in the shipment B. 100 randomly selected batteries C. 2% = the percent of the 100 selected batteries that do not have a full charge D. percent of the 1,000,000 batteries that do not have a full charge

From Sample to Population 1 (answer) A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge. Identify the parameter. A. 1,000,000 batteries in the shipment B. 100 randomly selected batteries C. 2% = the percent of the 100 selected batteries that do not have a full charge D. percent of the 1,000,000 batteries that do not have a full charge (correct)

From Sample to Population 2 A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge. Identify the statistic. A. 1,000,000 batteries in the shipment B. 100 randomly selected batteries C. 2% = the percent of the 100 selected batteries that do not have a full charge D. percent of the 1,000,000 batteries that do not have a full charge

From Sample to Population 2 (answer) A purchaser for a large convenience store chain wants to know if the shipment of 1,000,000 batteries he is receiving is a good one. He randomly selects 100 batteries from the shipment and tests their charge. Two of the batteries did not have a full charge. Identify the statistic. A. 1,000,000 batteries in the shipment B. 100 randomly selected batteries C. 2% = the percent of the 100 selected batteries that do not have a full charge (correct) D. percent of the 1,000,000 batteries that do not have a full charge

From Sample to Population 3 A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity. 413 said they did. Find the observed proportion (the sample proportion), p , of those who use parental controls. A) 1 1060 B) 413 1060 C) 1 413 D) 1 1060 E) 1 413

From Sample to Population 3 (answer) A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity. 413 said they did. Find the observed proportion (the sample proportion), p , of those who use parental controls. A) 1 1060 B) 𝟒𝟏𝟑 𝟏𝟎𝟔𝟎 (correct) C) 1 413 D) 1 1060 E) 1 413

From Sample to Population 4 The observed proportion, p , of parents who use parental controls is a sample statistic population parameter

From Sample to Population 4 (answer) The observed proportion, p , of parents who use parental controls is a sample statistic (correct) population parameter

Sampling Variability 1 A parameter is known and will not vary from sample to sample unknown and will not vary from sample to sample known and will vary from sample to sample unknown and will vary from sample to sample

Sampling Variability 1 (answer) A parameter is known and will not vary from sample to sample unknown and will not vary from sample to sample (correct) known and will vary from sample to sample unknown and will vary from sample to sample

Sampling Variability 2 A statistic is known and will not vary from sample to sample unknown and will not vary from sample to sample known and will vary from sample to sample unknown and will vary from sample to sample

Sampling Variability 2 (answer) A statistic is known and will not vary from sample to sample unknown and will not vary from sample to sample known and will vary from sample to sample (correct) unknown and will vary from sample to sample

Sampling Variability 3 The observed proportion, p , of parents who use parental controls will be the same from sample to sample be different from sample to sample be unknown

Sampling Variability 3 (answer) The observed proportion, p , of parents who use parental controls will be the same from sample to sample be different from sample to sample (correct) be unknown

Sampling Variability 4 In a study, it is most important to reduce bias reduce variability reduce both bias and variability use random sampling

Sampling Variability 4 (answer) In a study, it is most important to reduce bias reduce variability reduce both bias and variability (correct) use random sampling

Sampling Variability 5 In order to reduce bias, one should take a smaller sample size take a larger sample size be sure to use the best random sampling scheme

Sampling Variability 5 (answer) In order to reduce bias, one should take a smaller sample size take a larger sample size be sure to use the best random sampling scheme (correct)

Sampling Variability 6 In order to reduce variability, one should take a smaller sample size take a larger sample size be sure to use the best random sampling scheme

Sampling Variability 6 (answer) In order to reduce variability, one should take a smaller sample size take a larger sample size (correct) be sure to use the best random sampling scheme

Margin of Error and All That 1 Computing the margin of error when using a statistic to estimate a parameter is quantifying the bias telling us what sample size to use quantifying how much the statistic would vary from sample to sample quantifying how much the parameter would vary from sample to sample

Margin of Error and All That 1 (answer) Computing the margin of error when using a statistic to estimate a parameter is quantifying the bias telling us what sample size to use quantifying how much the statistic would vary from sample to sample (correct) quantifying how much the parameter would vary from sample to sample

Margin of Error and All That 2 Using a larger sample size increases margin of error decreases margin of error has no effect on margin of error

Margin of Error and All That 2 (answer) Using a larger sample size increases margin of error decreases margin of error (correct) has no effect on margin of error

Margin of Error and All That 3 A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity. Using the quick formula, compute the margin of error for 95% confidence. A) 1 1060 B) 413 1060 C) 1 413 D) 1 1060 E) 1 413

Margin of Error and All That 3 (answer) A recent Pew Research poll asked 1060 parents of 13–17 year olds whether they use parental controls for blocking, filtering, or monitoring their teen’s online activity. Using the quick formula, compute the margin of error for 95% confidence. A) 1 1060 B) 413 1060 C) 1 413 D) 𝟏 𝟏𝟎𝟔𝟎 (correct) E) 1 413

Confidence Statements A poll of 1,000 recent college grads revealed 9.6% believe Judith Sheindlin (Judge Judy) is on the Supreme Court. Suppose the MOE is 3% and the resulting confidence interval is (6.6,12.6). Choose the correct confidence statement. We are 95% confident that between 6.6 and 12.6% of recent college graduates think Judge Judy is on the Supreme Court. We are 95% confident that between 6.6 and 12.6% of recent college graduates sampled think Judge Judy is on the Supreme Court.

Confidence Statements (answer) A poll of 1,000 recent college grads revealed 9.6% believe Judith Sheindlin (Judge Judy) is on the Supreme Court. Suppose the MOE is 3% and the resulting confidence interval is (6.6,12.6). Choose the correct confidence statement. We are 95% confident that between 6.6 and 12.6% of recent college graduates think Judge Judy is on the Supreme Court. (correct) We are 95% confident that between 6.6 and 12.6% of recent college graduates sampled think Judge Judy is on the Supreme Court.

Sampling from Large Populations A simple random sample of size, n = 150, was taken from a population of size 250,000. Another simple random sample of size, n = 150, was taken from a population of size of 100,000. Which sample will yield a statistic with less variability? The first SRS will have less variability since the population is larger. The second SRS will have less variability since the population size is smaller. The variability will be similar since the sample sizes are the same.

Sampling from Large Populations (answer) A simple random sample of size, n = 150, was taken from a population of size 250,000. Another simple random sample of size, n = 150, was taken from a population of size of 100,000. Which sample will yield a statistic with less variability? The first SRS will have less variability since the population is larger. The second SRS will have less variability since the population size is smaller. The variability will be similar since the sample sizes are the same. (correct)