PG 11-20

Question 1

To perform any type of statistical procedure what do we require?

Answer 1

We require data.

Question 2

What is Bias?

Answer 2

Exists when some subjects or outcomes are systematically favored over others.

Question 3

What are the three types of bias that can be introduced into sampling?

Answer 3

Selection Bias, Non response Bias, and Response Bias.

Question 4

What is a Selection Bias?

Answer 4

Occur when one or more types of subjects are systematically excluded from the sample.

Question 5

What is an example of selection Bias?

Answer 5

Taking a sample of 200 students at a basketball game and asking if they’d want to pay to expand the arena, but those not at the game, their opinions aren’t included

Question 6

Relating to selection Bias, What is Undercoverage?

Answer 6

When an inference cannot be made to the entire population, but only a subset of the population, ex: students at the game, students not.

Question 7

What is Non Response Bias?

Answer 7

When an individual of the sample cannot be contacted or fails to respond.

Question 8

Example of Nonresponse Bias?

Answer 8

Throwing away survey, if 500 citizens are chosen, to represent each race an ethnic group and one race/ group does not respond, that is a non response bias.

Question 9

What is a Response Bias?

Answer 9

When respondents give inaccurate info or if the interview influences the subject to respond in a certain way due to the phrasing of the Q.

Question 10

What is Response Bias a big concern with?

Answer 10

Legal or social behavior issues.

Question 11

Example of Response Bias? (Committed a crime)

Answer 11

Have you ever committed a crime that involved inflicting injury to the body of another person?”

Due to social and legal concerns, the number of “no” responses will likely be higher than the actual number of people for which the correct response is “no”.

Question 12

Example 2 of Response Bias? (Airlines)

Answer 12

Do you feel safer flying on delta airlines as opposed to one of the other airlines? Response bias for delta airlines over others

Question 13

What does a Haphazard Sample involve?

Answer 13

Involves selecting a sample by some convenient mechanism that does NOT involve randomization.

Question 14

Examples of a Haphazard Sample? (there are two)

Answer 14

Mall survey- questions distributed to people

Campus survey- students questioned as they walk across campus

Question 15

What is a Volunteer Response sample?

Answer 15

Exists when subjects volunteer to be part of the study.

Question 16

Examples of Volunteer response?

Answer 16

Telephone call in polls, Internet surveys, newspaper surveys.

Question 17

What is the problem with Volunteer response samples?

Answer 17

Those who volunteer often have negatively strong opinions and they over represent those with strong opinions which skews data.

Question 18

What are Haphazard and Volunteer response samples prone to?

Answer 18

Bias, Particularly non response bias.

Question 19

Example of Haphazard and volunteer responses being Non Response Bias?

Answer 19

questions sent out to all vcu students asking how safe they feel on campus, respondents will most likely feel less safe and hope to generate change. causing a bias in the result.

Question 20

What are Random samples?

Answer 20

Samples in which subjects are chosen randomly to be in the sample.

Question 21

Why is random sampling good?

Answer 21

It is often representative of the pop. and is mostly free of bias.

Question 22

What is Probability Sampling Design?

Answer 22

When each subject of the population has a positive and equal chance of being selected for the sample.

Question 23

What does Probability Sampling design mainly do?

Answer 23

Reduce or eliminate bias.

Question 24

What is a Sampling Procedure?

Answer 24

Select a sample of the Pop. and only measure the subjects in sample.

Question 25

What is an Experimental design?

Answer 25

A treatment is imposed on the experimental units and a response is observed.

Question 26

What can you do as a result of an Experimental design?

Answer 26

You can compare the effect that the treatment is having on the response

Question 27

What should the Sample in an experiment be?

Answer 27

As REPRESENTATIVE of the population as possible, meaning the characteristics of sample should match those of the POP.

Question 28

Example of the sample being Representative of the Pop?

Answer 28

If the pop is 60 percent female then the sample should be that as well, if we think a persons sex will influence the response