Question 1

The head of the psychology department in a university is interested in finding the attitudes of her students toward implementing an internship as a requirement for completion of the degree. She obtains a list of all students who are psychology majors, randomly selects 100 students from the list, and surveys those who are selected. What type of sampling technique has she employed?

Accepted Answer

The head of the psychology department randomly selects 100 students from a list of all psychology majors, which is the definition of simple random sampling.

Question 2

A professor of mathematics wants to study how the students in his college perceive the subject. He walks into the college cafeteria and starts asking the students present there if they like mathematics. Which sampling technique is used by the professor in this scenario?

Accepted Answer

Haphazard sampling is a non-probability sampling technique in which the researcher chooses the sample based on convenience or accessibility. In this scenario, the professor is choosing to survey students in the college cafeteria because they are easily accessible to him at that time. He is not selecting a random sample or attempting to ensure representation from different subgroups (stratification). Therefore, haphazard sampling is the most appropriate choice for this scenario.

Question 3

It is important to use _____ sampling when researchers want to make precise statements about a specific population on the basis of the results of their survey.

Accepted Answer

Probability sampling allows researchers to randomly select participants from a population, which ensures that each member of the population has an equal chance of being included in the sample. This method reduces sampling bias and increases the accuracy of the results, which is crucial when making precise statements about the entire population. Haphazard, quota, and purposive sampling methods are more prone to bias and may not be representative of the entire population.

Question 4

The city council wants to examine the citizens' opinions about allowing dogs at the city's beaches. It prepares a list of all the blocks in the city and randomly selects 20% of the blocks to sample. It then surveys all residents of the selected city blocks. Which of the following sampling techniques does this sampling strategy exemplify?

Accepted Answer

This sampling strategy exemplifies cluster sampling, as the city blocks are treated as clusters and a random sample of blocks is selected to survey all residents within those clusters.

Question 5

To assess the presidential candidate preferences of the registered voters in Maricopa county, classified by social class and age, a researcher randomly selects voters from each subgroup according to their proportion in the entire county. This sampling technique is called _____ sampling.

Accepted Answer

The sampling technique described is stratified random sampling, which involves dividing the population into subgroups (in this case, social class and age) and then randomly selecting samples from each subgroup in proportion to their size in the entire population. This helps ensure that each subgroup is represented in the sample, which can improve the accuracy and representativeness of the results.

Question 6

Which of the following is an accurate statement about sample size?

Accepted Answer

Increasing the sample size usually leads to greater precision and accuracy in estimating population parameters, reducing sampling error and increasing statistical power. Therefore, a larger sample size is needed for increased accuracy. Choice A is incorrect because a smaller sample size tends to increase the size of the confidence interval due to increased variability and uncertainty. Choice B is also incorrect because sample size is not a constant percentage of population size, but depends on the research question, study design, sampling method, and desired level of precision. Choice D is incorrect because sample size is directly related to the confidence interval, as larger samples tend to produce narrower and more reliable confidence intervals.

Question 7

A researcher stands outside a restaurant and asks the youngsters leaving the restaurant if they enjoyed the food there. What type of sampling technique has the researcher employed?

Accepted Answer

The researcher has employed purposive sampling, as they have targeted a specific group of individuals (youngsters leaving the restaurant) for their opinions on the food. This is not a random sampling technique as the selection of individuals is not based on chance, but rather on a particular characteristic (leaving the restaurant). Stratified random sampling and cluster sampling are also not applicable here, as the researcher is not dividing the population into subgroups or selecting groups of individuals based on their proximity to each other.

Question 8

Which of the following best describes the relationship between sample size and confidence interval?

Accepted Answer

A larger sample size will lead to a more accurate estimate of the population parameter and therefore reduce the size of the confidence interval. This is because a larger sample size decreases the standard error of the mean, which is included in the confidence interval calculation.

Question 9

Ricardo wants to study the academic performance of graduate students in the U.S. First, he decides that he will study schools in only 15 states and randomly selects those states. He then randomly selects 30 schools from these 15 states. Over a period of 3 months, Ricardo travels to these 30 schools and studies the academic performance of their students. Identify the sampling technique used by Ricardo in this scenario.

Accepted Answer

Ricardo used cluster sampling because he randomly selected 15 states and then selected 30 schools from those states. The schools were selected as clusters, which is the defining aspect of cluster sampling.

Question 10

Which of the following is a probability sampling technique?

Accepted Answer

Simple random sampling is a probability sampling technique where each member of the population has an equal chance of being selected. This method ensures that the sample represents the population fairly, allowing for the generalization of results from the sample to the population. Other options like quota, haphazard, and purposive sampling are non-probability sampling techniques where not every member has a chance of being selected.

Question 11

You read in the newspaper that Proposition Q is favored by 57% of those polled. The results of the survey are said to be accurate within ±2 percentage points using a 95% level of confidence. From the information provided, it can be inferred that the actual population value is probably between _____.

Accepted Answer

The margin of error is ±2 percentage points, which means the actual population value could be up to 2 percentage points higher or lower than the reported value of 57%. So, the range would be 55% (57%-2%) to 59% (57%+2%). Therefore, the correct answer is choice C.

Question 12

_____ sampling has the advantage of a built-in assurance that the sample will accurately reflect the numerical composition of the various subgroups.

Accepted Answer

Stratified random sampling involves dividing the population into subgroups based on some characteristic and then randomly selecting samples from each subgroup. This ensures that the sample accurately represents the numerical composition of the subgroups and reduces sampling error. Therefore, it has the advantage of built-in assurance that the sample will accurately reflect the numerical composition of the various subgroups.

Question 13

With _____ sampling technique, each member of the population has an equal probability of being selected for the sample.

Accepted Answer

Simple random sampling is the technique where each member of the population has an equal probability of being selected for the sample. This method ensures that all individuals have an equal chance of being selected, avoiding bias and resulting in a representative sample of the population. Haphazard sampling relies on the discretion of the researcher and may not be representative. Cluster sampling involves dividing the population into clusters and selecting clusters at random, which may not be representative. Stratified random sampling divides the population into subgroups and then selects individuals from each subgroup, which can be useful for ensuring representation of different demographic groups, but is more complex than simple random sampling.

Question 14

Keziah stands outside a grocery store on the west side of the town and surveys exiting shoppers about their preference in frozen desserts. What type of sampling technique does Keziah's survey represent?

Accepted Answer

Keziah's survey represents a nonprobability sampling technique, as she is not using a random selection process and is only surveying shoppers who are exiting a specific grocery store on the west side of town. This type of sampling is often used in qualitative research, but may not provide a representative sample of the population.

Question 15

_____ indicates the amount of deviation in results obtained from a sample compared to the true population value.

Accepted Answer

Sampling error refers to the amount of deviation in results obtained from a sample compared to the true population value. Syntax error refers to errors in code or language structure. Halo effect refers to the tendency for a positive impression of a person or product in one area to influence one's opinion in another area. Sample variance is a measure of the spread of data within a sample.

Question 16

Angelika wants to study how sixth graders perform in math exams. She obtains a list of all districts in the state, randomly selects 5% of the districts, and administers achievement tests to all sixth graders in these districts. This sampling method used by Angelika is called _____ sampling.

Accepted Answer

The sampling method used by Angelika is cluster sampling as she obtained a list of all districts in the state and randomly selected a percentage of them to administer the achievement tests to all sixth graders in those districts.

Question 17

Jake's research methods instructor asks him to conduct a survey on "cheating" with a random sample of graduate students. To save time, he goes to the cafeteria and distributes the survey questionnaires among the students present there. In this case, the sampling method used by Jake is called _____ sampling.

Accepted Answer

The sampling method used by Jake is haphazard (also known as convenience) sampling, in which subjects are chosen because they are easily available or accessible. It is not a representative sample of the graduate student population and may be subject to bias. Simple random sampling would have been a better option to achieve a representative sample. Cluster sampling involves dividing the population into clusters and randomly choosing some of those clusters to sample from, which was not done here. Stratified random sampling involves dividing the population into groups (strata) based on certain characteristics and then randomly selecting participants from each group, which was also not done here.

Question 18

In which sampling technique do researchers choose a sample that reflects the numerical composition of various subgroups in a population?

Accepted Answer

Quota sampling allows researchers to choose a sample that reflects the numerical composition of various subgroups in a population by establishing quotas based on specific characteristics such as age, gender, or socioeconomic status. This technique ensures that the sample is representative of the population in terms of these demographic factors.

Question 19

Using a 95% confidence interval, Mike reports that 48% to 52% of the population favors Proposition D. The difference between 48% and 52% reflects the _____.

Accepted Answer

The range of 48% to 52% represents the margin of error or sampling error, which is the amount of variation that can be expected from the sample due to chance. It reflects the degree of uncertainty in the estimate and indicates that the true proportion of supporters in the population could be anywhere within this range with 95% probability. Census limits do not apply here since the entire population is not being surveyed. Confidence values are implied in the statement of the interval, but not what the difference signifies. Sample size could influence the precision of the estimate but is not directly related to the range of possible values.

Question 20

Political analysts are interested in analyzing the social perceptions of the current Democratic Party candidates in New York City. The number of registered Democrats and Republicans in the city is known. To form a sample of 1000, the analysts send out a team to sample the Democrats and the Republicans in proportion to the numbers registered. The team goes to major shopping malls and stops people as they enter, asking whether they are registered with one of the two parties. If so, the person is asked to fill out a questionnaire. The sampling technique used here would best be described as:

Accepted Answer

The sampling technique used in this scenario is stratified random sampling. This is because the population (Democrats and Republicans in New York City) is divided into strata (registered Democrats and Republicans), and a sample is then taken from each stratum in proportion to their representation in the population. This ensures that the sample is representative of the population and reduces the sampling error.

Quiz 7: Asking People About Themselves: Survey Research