Terms for Exam 2

Question 1

Define Population

Answer 1

The entire group of individuals which the researcher wants information.

Question 2

What is a variable?

Answer 2

A characteristic measured or recorded on each individual in the sample or population.

Question 3

What is something that takes on different values for different individuals?

Answer 3

A variable.

Question 4

Define Data production sample

Answer 4

A population that is selected and from which we actually collect information.

Question 5

What is data summarization?

Answer 5

The Data is graphed and the mean is computed.

Question 6

What does statistical inference do?

Answer 6

Conclusions are made about a population based on sample data.

Question 7

What are two Important pre-survey questions to ask?

Answer 7

1) Exactly what population do you want to describe?
i. e, how do you characterize what your studying?

2) Exactly what do you want to measure?
i. e what is meant by your variable, are you getting honest answers?

Question 8

What is a non random sample?

Answer 8

It is a sample chosen using personal judgement or human subjectivity to determine which individuals are in the sample and which are not. The probability of selecting a specific individual from the population can not be determined

Question 9

What are three bad examples of “non random samples?”

Answer 9

convenience sample
voluntary response sample
Mall intercept sample

Question 10

Define a Simple Random Sample (SRS):

Answer 10

A sample of size (n) chosen from the population in such a way that every set of (n) individuals has an equal chance to be the sample actually selected.

Question 11

What is a random digit table?

Answer 11

A list of digits 0,1,2,3,4,5,6,7,8,9 with two properties

Question 12

What are the two properties of random digit tables?

Answer 12

Each digit in the table is equally likely to be any of the ten digits 0-9

The entries are independent of each other; that means having knowledge of one part does not give information away concerning the other part.

Question 13

How to randomize data using a digit table

Answer 13

Say you have a population size of 105 and want to sample 25 individuals

1) assign each individual a label from 001-105 (or however many individuals there are)

2) Enter any line in the random digit table and select 25 ( meaning the # of your sample size) three digit number.
‘ignore all numbers greater than your population size (105)
‘skip numbers already selected

Question 14

What is an inference?

Answer 14

using information from a sample to draw a conclusion on a population
REMEMBER: An inference requires a random sample

Question 15

How do you find a stratified sample?

Answer 15

1) Classify the individuals of the population into strata (groups) according to some characteristics know prior to the survey
2) Choose a random sample from every strata (group)
3) Combine the samples from all the strata to form a complete sample

Question 16

For stratified sampling, a simple random sample is taken from _______ stratum.

Answer 16

EVERY

Question 17

After taking a stratified sample, the results from each strata are _________ to form a complete sample.

Answer 17

combined

Question 18

Why is a multi stage sample called multi staged?

Answer 18

Because it is done in stages

Question 19

How do you go about two stage sampling?

Answer 19

First a random sample of groups is selected;

Second individuals are randomly sampled from only the selected groups

Question 20

What the difference between stratified sampling and multi stage sampling?

Answer 20

Stratified you sample from all the groups

Mutli stage you sample from only some groups / and those groups are randomly selected

Question 21

How do you go about three stage sampling?

Answer 21

First select a random sample of groups
second sub groups are randomly sampled from only the selected groups
Third individuals are randomly sampled from only the selected sub groups

I.e The order goes
Selected Groups - Sub groups - Individuals

You can break this down even farther

Question 22

How do you define bias?

Answer 22

The tendency to systematically favor certain outcomes over others?
Calling people in the middle of the day on a land line to ask questions would probably over represent people such as stay at home moms and the elderly

Question 23

Bias due to under coverage occurs…

Answer 23

Because some groups in a population are left out when the sample is chosen
calling people at home will leave out the homeless and those in nursing homes

Question 24

Bias due to non response occurs…

Answer 24

When the individual chosen in the sample refuses to provide answers or can’t be contacted

Question 25

Bias due to response occurs…

Answer 25

When the respondent gives responses that influence the result in a systematic way.

Responseds will lie when they know something is illegal or if they don’t remember/don’t have information on topic

Question 26

Bias due to interviewer occurs…

Answer 26

how the interviewer conducts the interview.

Question 27

Bias due to question wording occurs…

Answer 27

due to wording of the question

Question 28

A part of the population from which we actually collect information. We use this to draw conclusions about the entire population.

Answer 28

Sample

Question 29

Systematic errors in the way a sample represents the population.

Answer 29

Bias

Question 30

Describes exactly how to choose a sample from the population.

Answer 30

Sampling Design

Question 31

Also denoted as SRS, this sample of size n consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be the sample actually selected.

Answer 31

Simple Random Sample

Question 32

A sample composed of separate SRSs chosen for different strata of a population (groups of individuals that are similar in some way that is important to the response).

Answer 32

Stratified Random Sample

Question 33

When some groups in the population are left out of the process of choosing the sample

Answer 33

undercoverage

Question 34

A sample composed of people who choose themselves by responding to a broad appeal. These samples are biased because people with strong opinions are most likely to respond.

Answer 34

voluntary response sample

Question 35

A survey conducted on a sample from the population of all individuals about which we desire information. We base conclusions about the population on data from the sample.

Answer 35

Sample Survey

Question 36

A long string of the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 with the following properties: 1.Each entry is equally likely to be any of the 10 digits 0 through 9. 2.The entries are independent of each other. The knowledge of one part gives no information about any other part.

Answer 36

Table of Random Digits

Question 37

In a statistical study, the entire group of individuals that we want information about.

Answer 37

Population

Question 38

When an individual chosen for the sample can’t be contacted or refuses to participate.

Answer 38

nonresponse