Question 1

Determine which of the four levels of measurement is most appropriate. Students' grades of A, B, or C, on a test.

Accepted Answer

Grades of A, B, or C on a test are ordinal because they represent a ranking or order of performance without implying a precise numerical difference between each grade.

Question 2

Which of the following is an inappropriate way to deal with missing data?

Accepted Answer

Ignoring missing data is inappropriate because it can lead to biased estimates and weaken the statistical power of the analysis. Proper handling techniques, such as deletion, substitution, or analysis of the pattern of missingness, should be considered instead.

Question 3

Identify which type of sampling is used. A tax auditor selects every 1000th income tax_ return that is received.

Accepted Answer

This is systematic sampling as the auditor is selecting every 1000th income tax return in a systematic manner. Random sampling would involve selecting returns randomly without any specific pattern or criteria. Stratified sampling would involve dividing the population into strata and selecting samples from each stratum based on certain criteria. Cluster sampling would involve selecting a group or cluster of returns and sampling from that group. Convenience sampling would involve selecting the most easily accessible returns, which may not be representative of the entire population.

Question 4

The good design of experiments includes blinding, _____________, and __________________.

Accepted Answer

The good design of experiments includes replication, which involves performing multiple trials to reduce the effects of chance and variability, and randomization, which involves randomly assigning subjects to different treatments to control for confounding variables. Blinding, which involves keeping either the subjects or the researchers unaware of the treatment assignments, is also an important consideration in reducing bias and ensuring the validity of the results. Choice A is incorrect because voluntary response samples can introduce bias and are not a desirable aspect of experimental design. Choice B is incorrect because internalization is not a relevant term in this context, and while randomization is important, it is not the only factor to consider in experimental design. Choice C is incorrect because replication and experimentation are not mutually exclusive, and experimentation is already implied as an essential component of experimental design.

Question 5

In a cross-sectional study, data are _____________.

Accepted Answer

In a cross-sectional study, data are observed, measured, and collected at one point of time. This type of study is often used to describe the prevalence of a particular health condition or behavior in a population at a specific point in time.

Question 6

Which of the following does not apply to the ratio level of measurement?

Accepted Answer

The ratio level of measurement requires there to be a natural zero starting point, data values can be compared in terms of ratios, and differences between data values are meaningful. However, data at the ratio level can and should be arranged in order, so option C is incorrect.

Question 7

Identify which type of sampling is used. A research team wants to study the demographics of college students in the U.S. using proportionate samples of students in majors reflecting actual
U.S. percentages.

Accepted Answer

The research team wants to reflect actual U.S. percentages, which means they are likely going to use stratified sampling to ensure that their sample reflects the proportions in the population.

Question 8

A marijuana survey included 1610 responses from a list of approximately 241,500,000 adults in the U.S. from which every 150,000th name was surveyed. Identify which of these types of
Sampling is used:

Accepted Answer

Systematic sampling is used when every nth item in the target population is selected for the sample, as described by selecting every 150,000th name.

Question 9

Which type of experiment separates subjects into groups that are similar but differ in ways that might affect the outcome of the experiment?

Accepted Answer

Randomized block design separates subjects into blocks or groups that are similar in some aspect, which might affect the outcome of the experiment. Within each block, subjects are then randomly assigned to different treatments. This design helps to reduce the effect of confounding variables and increases the precision of estimates. Completely randomized design assigns subjects randomly to different treatments without taking into account any potential sources of variations, Matched pairs design involves pairing subjects based on some similarity or matching criterion and then assigning them randomly to different treatments, whereas Rigorously controlled design involves controlling all possible sources of variations except the treatment of interest.

Question 10

Identify which type of sampling is used._ numbers, then interviews the voters corresponding to those numbers.

Accepted Answer

The answer of Identify which type of sampling is used._...

Question 11

Determine whether the given description corresponds to an observational study or an experiment. A political pollster reports that his candidate has a 10% lead in the polls with
10% undecided.

Accepted Answer

This is an example of an observational study because the pollster is simply observing and reporting on the results of the poll, rather than manipulating any variables or conducting an intervention.

Question 12

Determine whether the given description corresponds to an observational study or an experiment. A doctor gives a new medication to half of his patients with the flu and a placebo
To the other half of his patients with the flu.

Accepted Answer

This is an experiment because the doctor actively intervenes by giving a new medication to one group and a placebo to another, then observes the outcomes.

Question 13

Identify the type of study used. A town obtains current employment data by polling 10,000 of its citizens this month.

Accepted Answer

The study is collecting current data at one point in time from a subset of the population, without following them over time or looking back at past data. This is the definition of a cross-sectional study.

Question 14

A gardener has 75 clients, 45% of whom are businesses. Find the number of business clients.

Accepted Answer

To find the number of business clients, calculate 45% of 75 clients: $75 \times 0.45 = 33.75$. Since the number of clients must be a whole number, it rounds to 34 clients.

Question 15

Determine which of the four levels of measurement is most appropriate. Level of satisfaction of survey respondents.

Accepted Answer

Level of satisfaction is a subjective measure and can only be ranked in order from lowest to highest, making it an ordinal measurement. It cannot be measured on a scale with equal intervals or with a true zero point.

Question 16

The similarity between an ordinal level of measurement and an interval level of measurement is that _______________.

Accepted Answer

The answer of The similarity between an ordinal level of...

Question 17

Determine whether the given value is a statistic or a parameter. After taking the first exam, 15 of the students dropped the class.

Accepted Answer

The answer of Determine whether the given value is a...

Question 18

A marketing firm does a survey to find out how many people use a product. Of the one hundred people contacted, fifteen said they use the product. Identify the type of study used.

Accepted Answer

This is an observational study because the marketing firm is simply collecting data without manipulating any variables. They are observing and surveying the respondents to gather information on product usage.

Question 19

Determine which level of measurement is appropriate. A sample of children's balls are classified from softest to hardest.

Accepted Answer

The classification of the children's balls from softest to hardest represents an ordinal level of measurement because the data has a natural ordering or ranking. However, we do not have a fixed starting point or standardized units of measurement, which would be required for interval or ratio level measurement, respectively. Nominal level measurement would be appropriate if the balls were being classified by color or brand, where there is no inherent order or ranking.

Question 20

Determine which level of measurement is appropriate. Salaries of college professors.

Accepted Answer

Salaries of college professors are measured on a ratio scale because there is a true, meaningful zero point (professors can have a salary of $0) and the ratios between salaries are meaningful (one professor earning twice as much as another professor earns exactly twice as much).

Quiz 1: Introduction to Statistics