APS: Unit 3- Experimental Design

The Women's Health Study randomly assigned nearly 40,000 women over the age of 45 to receive either aspirin or a placebo for over 10 years to examine the effect of aspirin on cancer risk to healthy women. This long-term trial was best conducted as:

• a census.

• an observational study.

• a randomized comparative experiment.

• a single-blind randomized comparative experiment.

• a double-blind randomized comparative experiment.

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CCSS.HSS.IC.B.3

In the previous problem, supposed that the researchers suspected that women over the age of 55 may respond differently to the treatment. Given that a random sample of 40,000 women over the age of 45 has already been chosen, the study would have been improved by:

• a stratified sample, with strata determined by age.

• a stratified sample, with strata determined by gender.

• a block design, with blocks determined by age.

• a block design, with blocks determined by gender.

• a double-blind completely randomized design.

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Researchers were interested to know whether internal vehicle temperatures vary by outside temperatures. To evaluate this, temperature rise was measured continuously over a 60-minute period in a dark SUV on 16 different clear, sunny days with outside temperatures ranging from 72^oF to 96^oF. The researchers' method of analysis is best described as:

• a census.

• a survey.

• an observational study.

• a randomized comparative experiment.

• a single-blind randomized comparative experiment.

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CCSS.HSS.IC.B.3

Respondents to a randomly distributed questionnaire answered the question, "do you agree that nuclear weapons should never be used because they are immoral?" The study that uses the results of this questionnaire will most likely suffer from which types(s) of bias?

• undercoverage

• voluntary response

• response

• nonresponse

• all of the above

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CCSS.HSS.IC.B.6

A statistics teacher decides to compare this year's students to all those she has taught over the history of the course. She will use the students' examination performances as the method of comparison. Which of the following is true in this context?

• The mean performance of this year's students is a parameter.

• The mean performance of this year's students is a statistic.

• The mean of all except this year's students is a parameter.

• The mean of all students is a statistic.

• None of these is true.

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Left-handedness is the preference for the left hand over the right for everyday activities such as writing. Studies indicate that about 93% of the population may be characterized as right-handed. Researchers would like to conduct a study to determine if left-handed teens differ significantly in their ability to memorize facts than right-handed teens.

The explanatory variable in this study is:

• ability to memorize facts.

• age.

• handedness.

• researchers.

• none of the above.

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CCSS.HSS.IC.B.5

Left-handedness is the preference for the left hand over the right for everyday activities such as writing. Studies indicate that about 93% of the population may be characterized as right-handed. Researchers would like to conduct a study to determine if left-handed teens differ significantly in their ability to memorize facts than right-handed teens.

A random-number table is used to simulate the number of teens selected before a left-handed teen is found. A proper assignment of digits is:

• let the digits 0-6 represent a left-handed teen and 7-99 represent a right-handed teen; ignore repeats of numbers 7-99 until you get a number from 0-6.

• let the digits 0-6 represent a left-handed teen and 7-99 represent a right-handed teen; count repeats of number 7-99 and continue until you get a number from 0-6.

• let the digits 00-06 represent a left-handed teen and 07-99 represent a right-handed teen; ignore repeats of numbers 07-99 until you get a number from 00-06.

• let the digits 00-06 represent a left-handed teen and 07-99 represent a right-handed teen; count repeats of numbers 07-99 and continue until you get a number from 00-06.

• let the digits 01-07 represent a left-handed teen and 08-100 represent a right-handed teen; count repeats of numbers 08-100 and continue until you get a number from 01-07.

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Left-handedness is the preference for the left hand over the right for everyday activities such as writing. Studies indicate that about 93% of the population may be characterized as right-handed. Researchers would like to conduct a study to determine if left-handed teens differ significantly in their ability to memorize facts than right-handed teens.

Suppose the researchers concluded that the average number of words memorized by left-handed teens was statistically significantly higher than the average number memorized by right-handed teens. In this context, statistically significant means that:

• the number of words memorized by left-handed students exceeded the number memorized by right-handed students.

• the average number of words memorized by left-handed students exceeded the average number memorized by right-handed students.

• right-handed students tend to not do as well as left-handed students in memorizing words.

• it would be unlikely to observe an average difference as large as was observed by chance variation.

• a randomized, controlled experiment was conducted.

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Pollsters are interested in conducting a survey to determine if students who belonged to an online social network during college continued with it after graduation. They plan to randomly select 50 people from a list of registered voters. A problem with the proposed plan is that the:

• sampling frame may be different from the population of interest.

• sample size is too small.

• sample is a systematic random sample.

• sample was not stratified by political party.

• sampling design should incorporate multistage sampling.

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The purpose of randomization in an experiment is to:

• make the experiment seem fair.

• make the treatment groups as similar as possible.

• make the treatment groups as different as possible.

• create the blocks in an experiment.

• reduce variability within treatment groups.

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