Question 1

Which of the following best describes a 'sample' in statistics?

Accepted Answer

A subset of a population, examined in hope of learning about the population.

Question 2

A pharmaceutical company wants to test a new drug. They randomly assign patients to receive either the drug or a placebo and compare the outcomes. What type of study is this?

Accepted Answer

Experiment

Question 3

Which sampling method divides the population into groups that are similar within but different from each other, then samples from each group?

Accepted Answer

Stratified Random Sample

Question 4

A national polling service randomly selects cities from each region, then randomly selects households within those cities. What sampling method is being used?

Accepted Answer

Multistage Sample

Question 5

Which principle of experimental design is used to reduce the effects of identifiable attributes of subjects that may affect their responses but cannot be controlled?

Accepted Answer

Block

Question 6

In a completely randomized design, what is true about the assignment of treatments?

Accepted Answer

All experimental units have an equal chance of receiving any treatment.

Question 7

Which of the following is a common source of bias in sampling?

Accepted Answer

Nonresponse bias

Question 8

A researcher wants to estimate the average income of households in a city. She selects 10 neighborhoods and surveys every household in those neighborhoods. What sampling method is this?

Accepted Answer

Cluster Sampling

Question 9

Which of the following best defines a 'statistic' in the context of sampling?

Accepted Answer

A value calculated for sample data, used to estimate a population parameter.

Question 10

Suppose a sample of size $$n = 50 is $$drawn from a population. Which formula gives the sample mean $$\bar{x}$$?

Accepted Answer

$$\bar{x} = \frac{1}{n} \sum_{i=1}^{n} x_i$$

Question 11

A hospital wants to compare recovery times for two treatments. Patients are randomly assigned to each treatment, and recovery times are measured. What is the response variable?

Accepted Answer

Recovery time

Question 12

Which of the following is NOT a principle of experimental design?

Accepted Answer

Survey

Question 13

A study collects data on smoking habits and lung cancer rates by looking at medical records from the past 20 years. What type of study is this?

Accepted Answer

Retrospective Study

Question 14

Which of the following best describes a 'parameter'?

Accepted Answer

A numerically valued attribute of a model for a population.

Question 15

A simple random sample (SRS) of size $$n is $$drawn from a population. What is true about the probability of selection for each element?

Accepted Answer

Each element has an equal chance of selection.

Question 16

Which of the following is an example of sampling variability?

Accepted Answer

Two random samples from the same population yield different sample means.

Question 17

A researcher divides a population into regions and then randomly selects individuals from each region. What is this sampling method called?

Accepted Answer

Stratified Random Sampling

Question 18

Which formula represents the sample variance $$s^2$$ for a sample of size $$n$$?

Accepted Answer

$$s^2$$ = \frac{1}{n-1} \sum_{i=1}^{n} (x_i - \bar{x}$$)^2$$

Question 19

In an experiment, what is the term for the variable whose values are compared across different treatments?

Accepted Answer

Response Variable

Question 20

A poll asks a random sample of voters about their preferences in an upcoming election. What type of study is this?

Accepted Answer

Sample Survey

Fundamental Concepts in Sampling and Experimental Design for Statistics

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