Unit 3 - Collecting Data

Question 1

Observational Study

Answer 1

A researcher records what is already happening. Subjects choose what they do.

Question 2

Experiment

Answer 2

The researcher randomly assigns subjects to treatments. Subjects do not get to choose.

Question 3

Blind Experiment

Answer 3

The subjects do not know which treatment they are receiving

Question 4

Double Blind Experiment

Answer 4

The subjects AND the evaluators do not know who received which treatment.

Question 5

Placebo

Answer 5

A fake treatment (sugar pill, saline shot)

Question 6

Placebo Effect

Answer 6

Patients show improvement because they think they received treatment even though they only got a fake treatment

Question 7

Factors

Answer 7

What you are testing in the experiment. Same as the explanatory variable (x)

Question 8

Response Variable

Answer 8

What you measure at the end of the experiment. The y variable.

Question 9

Levels

Answer 9

The amounts or types of factors.

Examples:
Factor: Sleep; Levels: 5 hrs, 7 hrs, 9 hrs
Factor: Drug; Levels: Drug A, Drug B

Question 10

Block

Answer 10

A group of subjects for an experiment that are alike. Blocks must be split up to different treatments.

Question 11

Matched Pairs

Answer 11

A block of size 2. 2 subjects who are alike and are randomly assigned to different treatments.
A subject can be a pair for himself/herself.

Question 12

A strata

Answer 12

A group of people who are alike based on a characteristic. Used for sampling.

Question 13

Stratified Sampling

Answer 13

Each strata gets its own hat. Randomly select people from every strata to survey.

Question 14

A cluster

Answer 14

A mixed group of people that should be representative of the population

Question 15

Cluster Sampling

Answer 15

Put the names of the clusters in the hat. Randomly select one or more clusters and survey some/all the people in those clusters only.

Question 16

Systematic Sampling

Answer 16

Begin with the nth person. Sample every ___th person.

Question 17

Simple Random Sample

Answer 17

Every person in the population goes in the hat. Randomly select from the hat. Every person has an equal chance of being chosen. Every group of people has an equal chance of being chosen.

Question 18

Convenience Sample

Answer 18

Survey the people who are around you; who are convenient and easy to survey. A bad sampling method.

Question 19

Response Bias

Answer 19

People give answers that don’t represent their true feelings

• wording of the question is confusing
• question is about something embarassing
• intimidated by person asking the question
• wording of the question makes people feel like they should answer a certain way

Question 20

Voluntary Response Bias

Answer 20

People self select to answer the survey. Usually only people with strong opinions respond.

Question 21

Non-Response Bias

Answer 21

The researcher randomly selects people to participate in the survey, but those people do not respond

Question 22

Undercoverage

Answer 22

The survey is done in a way that leaves out a certain segment of the population

Question 23

Three Types of Experimental Design

Answer 23

1. Completely Randomized Design
2. Randomized Block Design
3. Matched Pairs

Question 24

Three Principles of Experimental Design

Answer 24

Control
Randomization
Replication

Question 25

What is control?

Answer 25

Treat all subjects the same except for the treatment to limit the effects of lurking variables.

Question 26

What is randomization?

Answer 26

Randomly assign subjects to the treatments. This helps reduce the effects of any lurking variables that cannot be controlled.

Question 27

What is replication?

Answer 27

Assigning multiple subjects to each treatment.

Question 28

Experimental Units

Answer 28

Non-human subjects.

• animals
• plants
• objects
• bacteria