On webwork2/Math214 Cao Spring2018/HW1/2/ 2 af the questions remain unanswered (

Question

On webwork2/Math214 Cao Spring2018/HW1/2/ 2 af the questions remain unanswered (1 pt) (a) A committee on community relations in a college town plans to survey local businesses about the importance of students as customen From telephone book listings, the committee chooses 249 businesses at random Ofthese, 69 return the questionnaire mailed by the commitee The poputation for this study is e A. all businesses in the college town B. the 69 businesses that returned the questionnaire. o C. the 249 businesses chosen. D. None of the above. (D) A sample or households in a community is selected at random from the telephone drectory in this commune. 4% of households have no telephone, 11% have only cel phones, and another 30% have unlisted telephone numbers The sample will certainly sumer tom A. undercoverage B. nonresponse C.false responses D. None of the above (c) An opinion poll contacts 1985 adults and asks them, - which poitical party do you think hnas beter ideas for leading the country in the 21st century? in al, 599 of the 1985 say,. The Democrats." The sample in this setting is A. the 599 people who chose the Democrats B. all 235 mition adults in the Unted states c. the 1985 people interviewed D. None of the above Note: You can eam partal credt on th s probiem O/R

Explanation / Answer

Committe on community relations

(a) The population for the study is:-

(A) all businesses in the college town.

Since the committe has chosen 249 businesses at random from the telephone book listings (the source of our sample) which contains the telephone numbers of all bussinesses in that particular college town, therefore the population would consist of the the same,

(b)The sample will certainly suffer from

(A) Undercoverage

As 30% of households have unlisted telephone numbers, 11% have only cell phones and 4% have no telephones, that brings the total to 45% households who are not in the telephone directory. This is nearly half of the population under consideration. So the sample that is selected will certainly suffer from undercoverage.

(c)The sample in this setting is

(C) the 1985 people interviewed.

Whatever be the population chosen for the purpose of the opinion pools, the sample that was finally selected was that of 1985 adults. Since we are asked about the sample, the correct answer is C.  

A group of college students believes that herbal tea

a) The explanatory variable in the experiement is

D) herbal tea

The explanatory variable, also know as the predictor is the variable about which you have information. In this case we have information about herbal tea which we are using to ascertain the emotional state of the residents.

b) Which of the following can be correctly concluded from the study?

D)The results of the study are not convincing because the effect of the herbal tea is confounded with several other factors

Now we cannot infer that the emotional state of the residents became better because of herbal tea. Maybe the visits of the college students to the local nursing home cheered the residents up OR it could be a lot of other factors as well. It is difficult to isolate the effect of different factors due to confounding.

c)The lurking variable in the experiment is

C) The emotional state of the residents

As mentioned above we are predicting the emotional state of the residents(response/lurking variable) from drinking herbal tea(the explanatory variable)

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