91影视

A 鈥渞andom survey鈥� was conducted of $3,274$people of the 鈥渕icroprocessor generation鈥� (people born since $1971$, the year the microprocessor was invented). It was reported that 48% of those individuals surveyed stated that if they had $\$2,000$to spend, they would use it for computer equipment. Also, $66\%$of those surveyed considered themselves relatively savvy computer users.

a. Do you consider the sample size large enough for a study of this type? Why or why not?

b. Based on your 鈥済ut feeling,鈥� do you believe the percents accurately reflect the U.S. population for those individuals born since $1971$? If not, do you think the percents of the population are actually higher or lower than the sample statistics? Why? Additional information: The survey, reported by Intel Corporation, was filled out by individuals who visited the Los Angeles Convention Center to see the Smithsonian Institute's road show called 鈥淎merica鈥檚 Smithsonian.鈥�

c. With this additional information, do you feel that all demographic and ethnic groups were equally represented at the event? Why or why not?

d. With the additional information, comment on how accurately you think the sample statistics reflect the population parameters

The Well-Being Index is a survey that follows trends of U.S. residents on a regular basis. There are six areas of health and wellness covered in the survey: Life Evaluation, Emotional Health, Physical Health, Healthy Behavior, Work Environment, and Basic Access. Some of the questions used to measure the Index are listed below. Identify the type of data obtained from each question used in this survey: qualitative, quantitative discrete, or quantitative continuous.

a. Do you have any health problems that prevent you from doing any of the things people your age can normally do?

b. During the past 30 days, for about how many days did poor health keep you from doing your usual activities?

c. In the last seven days, on how many days did you exercise for 30 minutes or more?

d. Do you have health insurance coverage?

In advance of the $1936$Presidential Election, a magazine titled Literary Digest released the results of an opinion poll predicting that the republican candidate Alf Landon would win by a large margin. The magazine sent post cards to approximately $10,000,000$prospective voters. These prospective voters were selected from the subscription list of the magazine, from automobile registration lists, from phone lists, and from club membership lists. Approximately $2,300,000$people returned the postcards.

a. Think about the state of the United States in $1936$. Explain why a sample chosen from magazine subscription lists, automobile registration lists, phone books, and club membership lists was not representative of the population of the United States at that time.

b. What effect does the low response rate have on the reliability of the sample?

c. Are these problems examples of sampling error or non sampling error?

d. During the same year, George Gallup conducted his own poll of $30,000$prospective voters. These researchers used a method they called "quota sampling" to obtain survey answers from specific subsets of the population. Quota sampling is an example of which sampling method described in this module?

Crime-related and demographic statistics for $47$US states in $1960$were collected from government agencies, including the FBI's Uniform Crime Report. One analysis of this data found a strong connection between education and crime indicating that higher levels of education in a community correspond to higher crime rates. Which of the potential problems with samples discussed in Section $1.2$could explain this connection?

YouPolls is a website that allows anyone to create and respond to polls. One question posted April $15$asks:

鈥淒o you feel happy paying your taxes when members of the Obama administration are allowed to ignore their tax liabilities?鈥�$\left[5\right]$

As of April $25,11$people responded to this question. Each participant answered 鈥淣O!鈥�

Which of the potential problems with samples discussed in this module could explain this connection?

A scholarly article about response rates begins with the following quote:

鈥淒eclining contact and cooperation rates in random digit dial (RDD) national telephone surveys raise serious concerns about the validity of estimates drawn from such research.鈥�^{$\left[6\right]$}The Pew Research Center for People and the Press admits: 鈥淭he percentage of people we interview 鈥� out of all we try to interview 鈥� has been declining over the past decade or more.鈥�^{$\left[7\right]$}

a. What are some reasons for the decline in response rate over the past decade?

b. Explain why researchers are concerned with the impact of the declining response rate on public opinion polls.

A study was done to determine the age, number of times per week, and the duration (amount of time) of residents using a local park in San Antonio, Texas. The first house in the neighborhood around the park was selected randomly, and then the resident of every eighth house in the neighborhood around the park was interviewed.

鈥淒uration (amount of time)鈥� is what type of data?

a. qualitative(categorical); b. quantitative discrete; c. quantitative continuous

Fifty part-time students were asked how many courses they were taking this term. The (incomplete) results are shown below:

a. Fill in the blanks in Table $1.33$.

b. What percent of students take exactly two courses?

c. What percent of students take one or two courses?

Sixty adults with gum disease were asked the number of times per week they used to floss before their diagnosis. The (incomplete) results are shown in Table $1.34.$

a. Fill in the blanks in Table$1.34.$

b. What percent of adults flossed six times per week?

c. What percent flossed at most three times per week?

Nineteen immigrants to the U.S were asked how many years, to the nearest year, they have lived in the U.S. The data are as follows:

Table $1.35$was produced.

a. Fix the errors in Table $1.35$. Also, explain how someone might have arrived at the incorrect number(s).

b. Explain what is wrong with this statement: 鈥�$47$percent of the people surveyed have lived in the U.S. for $5$测别补谤蝉.鈥�

c. Fix the statement in b to make it correct.

d. What fraction of the people surveyed have lived in the U.S. five or seven years?

e. What fraction of the people surveyed have lived in the U.S. at most $12$years?

f. What fraction of the people surveyed have lived in the U.S. fewer than $12$years?

g. What fraction of the people surveyed have lived in the U.S. from five to $20$years, inclusive?