The news article goes on to say: “The theoretical errors do not take into account a margin of additional error resulting from the various practical difficulties in taking any survey of public opinion.” List some of the “practical difficulties” that may cause errors in addition to the percentage point margin of error. Pay particular attention to the news article’s description of the sampling method.
The practical difficulty is " Nonresponse bias is the result of not having data for everybody in the sample ".
The theoretical errors do not take into account a margin of additional error resulting from the various practical difficulties in taking any survey of public opinion.
Some of the practical difficulties:
Selection bias will exclude part of the population
Measurement of response bias will use a method that gives different values from the true value
Nonresponse bias is the result of not having data for everybody in the sample.
A researcher plans to use a random sample of families to estimate the mean monthly family income for a large population. A confidence interval based on the sample would be ______ than a 90% confidence interval.
(a) narrower and would involve a larger risk of being incorrect
(b) wider and would involve a smaller risk of being incorrect
(c) narrower and would involve a smaller risk of being incorrect
(d) wider and would involve a larger risk of being incorrect
(e) wider, but it cannot be determined whether the risk of being incorrect would be larger or smaller
Losing weight A Gallup Poll in November found that of the people in its sample said “Yes” when asked, “Would you like to lose weight?” Gallup announced: “For results based on the total sample of national adults, one can say with 95% confidence that the margin of (sampling) error is percentage points.”
(a) Explain what the margin of error means in this setting.
(b) State and interpret the confidence interval.
(c) Interpret the confidence level.
Alcohol abuse has been described by college presidents as the number one problem on campus, and it is an important cause of death in young adults. How common is it? A survey of 10,904 randomly selected U.S. college students collected information on drinking behavior and alcohol-related problems.9 The researchers defined “frequent binge drinking” as having five or more drinks in row three or more times in the past two weeks. According to this definition, 2486 students were classified as frequent binge drinkers
Check conditions for constructing a confidence interval for the parameter
64. Vitamin C content Several years ago, the U.S. Agency for International Development provided metric tons of corn-soy blend (CSB) foremergency relief in countries throughout the world. CSB is a highly nutritious, low-cost fortified food. As part of a study to evaluate appropriate vitamin C levels in this food, measurements were taken on samples of CSB produced in a factory. The following data are the amounts of vitamin C,
measured in milligrams per grams (mg/100 g) of blend, for a random sample of size from one production run:Construct and interpret a confidence interval for the mean amount of vitamin C M in the CSB from this production run.
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