Unit 1 Chapters 10-12

Question 1

Ch 10: Define “Random”

Answer 1

An outcome is random if we know the possible values it can have, but not which particular value it takes.

Question 2

Ch 10: What is a “Simulation”

Answer 2

A simulation mimics a real-life event by using random numbers to represent the outcomes of real events.

Question 3

Ch 10: What is a “Simulation Component?”

Answer 3

A component uses equally likely random digits to model simple random occurrences whose outcomes may not be equally likely.

Question 4

Ch 10: What is a “Trial”

Answer 4

The sequence of several components representing events that we are “pretending” will take place.

Question 5

Ch 10: Define “Response Variable”

Answer 5

Values of the response variable record the results of each trial with respect to what we were interested in.

Question 6

Ch 11: Define “Population”

Answer 6

The entire group of individuals or instances about whom we hope to learn.

Question 7

Ch 11: Define “Sample”

Answer 7

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

Question 8

Ch 11: What is a “Sample Survey?”

Answer 8

A study that asks questions of a sample drawn from some population in hope of learning something about the entire population.

Question 9

Ch 11: Name four types of “Bias” in a survey.

Answer 9

1) relying on voluntary response; 2) undercoverage of the population; 3) nonresponse bias; 4) response bias

Question 10

Ch 11: What minimizes the risk of bias in a survey?

Answer 10

Randomization. Each individual is give a fair, random chance of selection.

Question 11

Ch 11: What is “Sample Size?”

Answer 11

The number of individuals in a sample.

Question 12

Ch 11: What is a “Census?”

Answer 12

A sample that consists of the entire population.

Question 13

Ch 11: Define the term “Population Parameter”

Answer 13

A numerically valued attribute (mean, standard deviation, proportion, correlation, regression coefficient) of a model for a population.

Question 14

Ch 11; What is a “Sample Statistic?”

Answer 14

Values calculated from sample data (mean, standard deviation, proportion, correlation, regression coefficient), used to estimate a population parameter

Question 15

Ch 11: When is a sample “representative?”

Answer 15

A sample is representative if the statistics computed from it accurately reflect the population parameters.

Question 16

Ch 11: “SRS”

Answer 16

A “Simple Random Sample” of sample size n is a sample in which each set of n elements in the population has an equal chance of selection.

Question 17

Ch 11: What is the “Sampling Frame?”

Answer 17

The list of individuals from whom the sample is drawn. Individuals who may be in the population of interest, but not in the sample frame may NOT be included in the sample.

Question 18

Ch 11: Define Sampling Variability

Answer 18

The natural tendency of randomly drawn samples to differ from one another.

Question 19

Ch 11: What is a “Stratified Random Sample?”

Answer 19

A sampling design in which the population is divided into several subpopulations, or strata. Random samples are then drawn from each stratum.

Question 20

Ch 11: What is a “Cluster Sample?”

Answer 20

A sampling design in which entire groups, or clusters, are chosen at random. Cluster sampling is usually selected as a matter of convenience, practicality, or cost.

Question 21

Ch 11: Define “Multistage Sampling”

Answer 21

Sampling schemes that combine several sampling methods.

Question 22

Ch 11: What is “Systematic Sampling?”

Answer 22

A sample drawn by systemically selecting individuals from a sampling frame (ie: select a random starting point, then choose every 5th name from a list)

Question 23

Ch 11: What is a “Pilot Study?”

Answer 23

A small trial run of a survey to check whether questions are clear.

Question 24

Ch 11: What is “Voluntary Response Bias?”

Answer 24

Bias introduced to a sample when individuals can choose on their own whether to participate in the sample.

Question 25

Ch 11: Name the problem with “Convenience Samples”

Answer 25

These samples include individuals who are conveniently available. They often fail to be representative because everyone in the population is not equally convenient to sample.

Question 26

Ch 11: How does “Undercoverage” bias a sample?

Answer 26

In the sample, a part of the population is given less representation than it has in the population.

Question 27

Ch 11: “Nonresponse Bias” occurs when…

Answer 27

a large fraction of those sampled fails to respond. Those who do respond are likely to NOT represent the entire population.

Question 28

Ch 11: Define “Response Bias”

Answer 28

Anything in a survey design that influences responses falls under the heading of response bias. Example: wording of question may suggest a favored response.

Question 29

Ch 12: What is an “Observational Study”

Answer 29

A study, retrospective or prospective, based on data in which factors were not manipulated. Researchers observe factors.

Question 30

Ch 12: What are the main features of an “Experiment”

Answer 30

1) manipulates factor levels to create treatments; 2) randomly assigns subjects to treatment levels; 3) compares the responses across treatment levels

Question 31

Ch 12: Define “Random Assignment”

Answer 31

An experimenter assigns experimental units to treatment groups in a random way (slips of paper, random numbers, etc)

Question 32

Ch 12: What is a “Factor?”

Answer 32

A variable whose levels are manipulated by the experimenter.

Question 33

Ch 12: Define “Response”

Answer 33

A variable whose values are compared across different treatments.

Question 34

Ch 12: What are “Experimental Units?”

Answer 34

Individuals on whom an experiment is performed.

Question 35

Ch 12: What is the “level” of a factor?

Answer 35

The specific values that the experimenter chooses for a factor.

Question 36

Ch 12: What is a “Treatment?”

Answer 36

The process, intervention or other controlled circumstance applied to randomly assigned experimental units.

Question 37

Ch 12: What are the “Principles of Experimental Design?”

Answer 37

1) Control; 2) Randomize; 3) Replicate; 4) Block

Question 38

Ch 12: What is true about a “Completely Randomized Design?”

Answer 38

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

Question 39

Ch 12: What does it mean for an observed difference to be “Statistically Significant?”

Answer 39

The observed difference is too large for us to believe that it is likely to have occurred naturally.

Question 40

Ch 12: What is assigned to a “Control Group?”

Answer 40

Experimental units assigned to a baseline treatment level.

Question 41

Ch 12: Describe the concept of “Blinding”

Answer 41

Any individual associated with an experiment who is not aware of how subjects have been allocated to treatment groups is said to be blinded.

Question 42

Ch 12: What is a “Placebo?”

Answer 42

A treatment known to have no effect, administered to one group so that all groups experience the same conditions.

Question 43

Ch 12: Describe the “Placebo Effect”

Answer 43

The tendency of many human subjects to show a response even when administered a placebo.

Question 44

Ch 12: Describe “Blocking”

Answer 44

Grouping similar experimental units. In this way, we reduce the variability in the differences between blocks, and the differences between treatments is better observed.

Question 45

Ch 12: Describe “Randomized Block Design”

Answer 45

The subjects are randomly assigned to treatments within blocks.

Question 46

Ch 12: When are factors “Confounded?”

Answer 46

When the levels of one factor are associated with the levels of another factor in such a way that their effects cannot be separated.