Question 1

Determine whether the study is an observational study or an experiment.
-A pollster obtains a sample of students and asks them how they will vote on an upcoming referendum.

Accepted Answer

This is an observational study because the pollster is simply observing and recording how the students plan to vote on the referendum. The pollster is not manipulating any variables or interventions to see how they affect the outcome. This is an observational study because the pollster is simply observing and recording how the students plan to vote, without any manipulation or intervention in the voting process.

Question 2

Identify the sampling technique used.
-Thirty-five sophomores, 24 juniors and 25 seniors are randomly selected from 388 sophomores, 418 juniors and 573 seniors at a certain high school.

Accepted Answer

The technique used is stratified sampling because the population is divided into three strata based on grade level, and a random sample is taken from each stratum. This sampling technique is stratified because the population (high school students) is divided into three strata (sophomores, juniors, and seniors) and a random sample is taken from each stratum.

Question 3

Identify the sampling technique used.
-A researcher randomly selects and interviews fifty male and fifty female teachers.

Accepted Answer

This is an example of stratified sampling because the researcher has separated the population (teachers) into two strata (male and female) and then randomly selected respondents from each stratum. This ensures that both genders are represented in the sample and the results can be generalized to the population as a whole. The researcher is purposely selecting both male and female teachers, indicating a desire to have representation from both genders. This is an example of stratified sampling, as the population is divided into subgroups (male and female) and a random sample is taken from each subgroup.

Question 4

Determine whether the study is an observational study or an experiment.
-A medical researcher obtains a sample of adults suffering from diabetes. She randomly assigns 67 people to a treatment group and 67 to a placebo group. The treatment group receives a medication over a period of three
Months and the placebo group receives a placebo over the same time frame. At the end of three months the
Patientsʹ symptoms are evaluated.

Accepted Answer

This is an experiment because the researcher is manipulating the treatment group by giving them medication and comparing their symptoms to those of the placebo group. The random assignment of patients to the treatment and placebo groups also helps reduce the potential for confounding variables, which is a characteristic of an experiment. This is an experiment because the researcher is manipulating the variable (providing medication to the treatment group) and randomly assigning participants to groups. The goal is to determine if the medication has an effect on the symptoms of diabetes.

Question 5

Identify the sampling technique used.
-Based on 11,000 responses from 48,000 questionnaires sent to its alumni, a major university estimated that the annual salary of its alumni was $118,000 per year.

Accepted Answer

This is an example of random sampling because the questionnaires were likely sent out to a broad, random selection of alumni without subdividing them into specific groups or clusters.

Question 6

Determine whether the study is an observational study or an experiment.
-A researcher obtained a random sample of 100 smokers and a random sample of 100 nonsmokers. After interviewing all 200 participants in the study, the researcher compared the rate of depression among the
Smokers with the rate of depression among nonsmokers.

Accepted Answer

The researcher did not manipulate any variables or assign any groups, but instead observed and compared rates of depression among two pre-existing groups (smokers and nonsmokers). This fits the definition of an observational study. This study is an observational study because the researcher is merely observing and comparing the rates of depression among smokers and non-smokers without manipulating any variables. In an experiment, the researcher would need to manipulate one variable (e.g. have smokers quit smoking) and compare the effect on the rates of depression.

Question 7

Provide an appropriate response.
-Explain why data expressed with the Celsius temperature scale is at the interval level of measurement rather
than the ratio level.

Accepted Answer

The answer of Provide an appropriate response.
-Explain why data expressed...

Question 8

Identify the sampling technique used.
-A researcher for an airline interviews all of the passengers on five randomly selected flights.

Accepted Answer

The researcher is using cluster sampling by selecting entire groups (in this case, flights) at random, rather than selecting individual passengers from all flights.

Question 9

Provide an appropriate response.
-Explain what bias there is in a study done entirely online.

Accepted Answer

The answer of Provide an appropriate response.
-Explain what bias there...

Question 10

Identify the sampling technique used.
-Every fifth person boarding a plane is searched thoroughly.

Accepted Answer

This is a systematic sampling technique where every fifth person is selected for the search. In this scenario, every fifth person boarding a plane is selected for a thorough search, which makes it a systematic sampling technique.

Question 11

Identify the data setʹs level of measurement.
-the data listed on the horizontal axis in the graph

Accepted Answer

The answer of Identify the data setʹs level of measurement.
-the...

Question 12

Provide an appropriate response.
-Explain the differences between the interval and ratio levels of measurement.

Accepted Answer

The answer of Provide an appropriate response.
-Explain the differences between...

Question 13

Identify the sampling technique used.
-A community college student interviews everyone in a statistics class to determine the percentage of students that own a car.

Accepted Answer

This is a convenience sampling technique because the researcher is only selecting participants who are easily accessible and available to them (i.e. the statistics class). The student is interviewing everyone in a statistics class, which is a convenient sample as they are easily accessible to the student.

Question 14

Identify the sampling technique used.
-At a local community college, five statistics classes are randomly selected out of 20 and all of the students from each class are interviewed.

Accepted Answer

This is an example of cluster sampling because entire groups (or clusters) are randomly selected, in this case, the five statistics classes out of 20, and all members of the selected clusters are included in the sample.

Question 15

Determine whether the study is an observational study or an experiment.
-A scientist was studying the effects of a new fertilizer on crop yield. She randomly assigned half of the plots on a farm to group one and the remaining plots to group two. On the plots in group one, the new fertilizer was
Used for a year. On the plots in group two, the old fertilizer was used. At the end of the year the average crop
Yield for the plots in group one was compared with the average crop yield for the plots in group two.

Accepted Answer

This is an experiment because the scientist randomly assigned plots to different treatments (using new or old fertilizer) and compared the results. This type of study allows for cause-and-effect conclusions to be drawn. This is an experiment because the scientist randomly assigned plots to two different groups and purposely manipulated the type of fertilizer used on each group. The scientist then compared the crop yield between the two groups at the end of the year. It is not an observational study because the scientist was actively manipulating one variable (the type of fertilizer).

Question 16

Provide an appropriate response.
-A report sponsored by the California Citrus Commission stated that cholesterol levels can be lowered by
drinking at least one glass of a citrus product each day. Determine if the report is biased.

Accepted Answer

The answer of Provide an appropriate response.
-A report sponsored by...

Question 17

Provide an appropriate response.
-A local newspaper ran a survey by asking, ʺDo you support the deployment of a weapon that could kill
millions of innocent people?ʺ Determine whether the survey question is biased.

Accepted Answer

The answer of Provide an appropriate response.
-A local newspaper ran...

Question 18

Determine whether the study is an observational study or an experiment.
-The personnel director at a large company would like to determine whether the company cafeteria is widely used by employees. She calls each employee and asks them whether they usually bring their own lunch, eat at
The company cafeteria, or go out for lunch.

Accepted Answer

This is an observational study because the personnel director is simply observing and collecting data on employee lunch habits without manipulating any variables or implementing a treatment. This is an observational study because the personnel director is not manipulating any variables or introducing any treatments. She is simply observing and collecting data on the employees' lunch choices.

Question 19

Identify the experimental units and treatments used in the experiment.
-A medical researcher center wants to test the effectiveness of a new diabetes medication. The company
identifies 82 adults suffering from a similar form of diabetes. The subjects are randomly assigned to two
groups. One group is given a medication and the other is given a placebo that looks exactly like the medication.
After three months, the subjectsʹ symptoms are studied and compared.

Accepted Answer

The answer of Identify the experimental units and treatments used...

Question 20

Determine whether the study is an observational study or an experiment.
-A poll is conducted in which professional musicians are asked their ages.

Accepted Answer

This is an observational study because the researchers are not manipulating any variables or assigning participants to different groups. They are simply observing and collecting data on the ages of professional musicians. This is an observational study because the researchers are simply observing and collecting data on the ages of professional musicians. They are not manipulating any variables or controlling any factors, which is what would make it an experiment.

Quiz 1: Introduction to Statistics

Determine whether the study is an observational study or an experiment. -A pollster obtains a sample of students and asks them how they will vote on an upcoming referendum.

Identify the sampling technique used. -Thirty-five sophomores, 24 juniors and 25 seniors are randomly selected from 388 sophomores, 418 juniors and 573 seniors at a certain high school.

Identify the sampling technique used. -A researcher randomly selects and interviews fifty male and fifty female teachers.

Identify the sampling technique used. -Based on 11,000 responses from 48,000 questionnaires sent to its alumni, a major university estimated that the annual salary of its alumni was $118,000 per year.

Provide an appropriate response. -Explain why data expressed with the Celsius temperature scale is at the interval level of measurement rather than the ratio level.

Identify the sampling technique used. -A researcher for an airline interviews all of the passengers on five randomly selected flights.

Provide an appropriate response. -Explain what bias there is in a study done entirely online.

Identify the sampling technique used. -Every fifth person boarding a plane is searched thoroughly.

Identify the data setʹs level of measurement. -the data listed on the horizontal axis in the graph

Provide an appropriate response. -Explain the differences between the interval and ratio levels of measurement.

Identify the sampling technique used. -A community college student interviews everyone in a statistics class to determine the percentage of students that own a car.

Identify the sampling technique used. -At a local community college, five statistics classes are randomly selected out of 20 and all of the students from each class are interviewed.

Provide an appropriate response. -A report sponsored by the California Citrus Commission stated that cholesterol levels can be lowered by drinking at least one glass of a citrus product each day. Determine if the report is biased.

Provide an appropriate response. -A local newspaper ran a survey by asking, ʺDo you support the deployment of a weapon that could kill millions of innocent people?ʺ Determine whether the survey question is biased.

Determine whether the study is an observational study or an experiment. -A poll is conducted in which professional musicians are asked their ages.