Question 1

Which of the following best describes an observational study?

Accepted Answer

A researcher observes and measures characteristics of interest without influencing the subjects.

Question 2

A pharmaceutical company wants to test a new drug. They randomly assign 500 patients to receive the drug and 500 to receive a placebo. Neither the patients nor the doctors know who receives the drug. What type of experimental design is this?

Accepted Answer

Double-blind experiment

Question 3

Which of the following is an example of a stratified sample?

Accepted Answer

Dividing a population into age groups and randomly selecting members from each group

Question 4

A researcher wants to study the effects of a new fertilizer on plant growth. She divides the plants into two groups based on species, then randomly assigns half of each species to receive the fertilizer and the other half to serve as a control. What sampling technique is being used?

Accepted Answer

Randomized block design

Question 5

Which of the following is a potential problem with using a convenience sample?

Accepted Answer

It often leads to biased results that are not representative of the population.

Question 6

In a clinical trial, some patients report improvement after receiving a sugar pill instead of the actual medication. This is an example of:

Accepted Answer

The placebo effect

Question 7

A city council wants to estimate the average commute time for all city residents. They divide the city into neighborhoods and randomly select all residents from three neighborhoods to survey. What sampling method is this?

Accepted Answer

Cluster sampling

Question 8

Which of the following best describes replication in experimental design?

Accepted Answer

Repeating the experiment with a large group of subjects to improve validity.

Question 9

A researcher wants to select a sample of 50 students from a university with 5,000 students. She assigns each student a number and uses a random number generator to select 50 students. What type of sampling is this?

Accepted Answer

Simple random sampling

Question 10

Which of the following is an example of a confounding variable?

Accepted Answer

A researcher cannot tell if increased sales are due to a new advertising campaign or a holiday season.

Question 11

A researcher wants to study the effect of exercise on blood pressure. She pairs subjects by age and gender, then randomly assigns one from each pair to the exercise group and the other to the control group. What experimental design is this?

Accepted Answer

Matched-pairs design

Question 12

Which of the following statements about systematic sampling is correct?

Accepted Answer

A starting value is chosen at random, then every kth member is selected.

Question 13

A simulation is most useful when:

Accepted Answer

The situation is impractical or dangerous to recreate in real life.

Question 14

Which of the following is NOT a key element of a well-designed experiment?

Accepted Answer

Convenience

Question 15

A survey is conducted by calling people listed in the phone book. What is a potential source of bias in this survey?

Accepted Answer

People without landlines are excluded from the survey.

Question 16

Which of the following best describes a census?

Accepted Answer

A count or measure of an entire population.

Question 17

A researcher divides a population into groups based on income level and then randomly selects some members from each group. What sampling method is this?

Accepted Answer

Stratified sampling

Question 18

Which of the following is a sampling error?

Accepted Answer

The difference between the results of a sample and those of the population.

Question 19

A researcher wants to study the effect of a new teaching method. She randomly assigns students to either the new method or the traditional method. After the semester, she compares test scores. What type of study is this?

Accepted Answer

Experiment

Question 20

Which of the following is the correct formula for the probability of selecting a specific member in a simple random sample of size $$n$$ from a population of size $$N$$?

Accepted Answer

$$P = \frac{1}{N}$$

Chapter 1: Introduction to Statistics – Data Collection and Experimental Design

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