Chapter #4b - 09/25/24

Question 1

define a “unit” :

Answer 1

is a single individual or object to be measured

Question 2

define the “population” :

Answer 2

is the entire collection of units about which we would like information or the entire collection of measurements we would have if we could measure the whole population

Question 3

what is another word for “the population” ?

Answer 3

universe

Question 4

define “sample” :

Answer 4

the sample is the collection of units we actually measure or the collection of measurements we actually obtain

Question 5

define “the sampling frame” :

Answer 5

is a list of units from which the sample is chosen. (ideally it includes the whole population ; ex. list of students enrolled at UWO, list of subscribers of a magazine, list of taxpayers)

Question 6

define “sample survey” :

Answer 6

when measurements are taken on a subset, or sample, of units from the population

Question 7

define “census” :

Answer 7

is a survey in which the entire population is measured

Question 8

an opinion poll calls 5000 randomly chosen residential telephone numbers in lonfon and asks to speak with an adult member of the household. the interview asks “how many movies have you watched in a movie theater in the past 12 months?”. in all, 575 people responded. the sample in this survey is …

a) all adults living in london
b) the 5000 residental phone numbers called
c) the 575 people who respondents

Answer 8

c) the 575 people who respondents

Question 9

what is a unit ?

Answer 9

An individual element or person from which data is collected in a study

Question 10

what is a population ?

Answer 10

The entire group of individuals or items that you want to study or gather information about

Question 11

what is a sample ?

Answer 11

smaller group selected from the population, used to represent the entire population in a study

Question 12

what is a sample survey ?

Answer 12

A method of collecting data from a sample of the population to make inferences about the entire population

Question 13

what is a sample frame ?

Answer 13

A list or database of all the units in the population from which the sample is drawn.

Question 14

what is a census ?

Answer 14

A survey where data is collected from every unit in the entire population, rather than just a sample

Question 15

define the “rate of nonresponse” :

Answer 15

is the percentage of people in a survey who don’t answer the questions

Question 16

FILL IN THE BLANK

with proper sampling methods, based on a sample of 1500 adults, we can almost certainly estimate to within ___%, the percentage of the entire population who have a certain trait or opinion

Answer 16

3%

Question 16

a polling firm sends an online questionnaire to 3000 employees at a tech company, asking, “do you work remotely more than 3 days a week?”. 450 employees complete the survey. the population in this surveu is :

a) all employees at the tech company
b) the 3000 employees invited to participate
c) the 450 employees who respondents

Answer 16

a) all employees at the tech company

Question 17

what can a high nonresponse rate lead to ?

Answer 17

can lead to biased results because it may mean that certain groups are not represented

Question 18

define “margin of error” :

Answer 18

is a measure of how much the results of a survey could differ from the true values in the population. It shows the range within which the actual value likely falls, usually expressed as a percentage

Question 19

how do you calculate the margin of error ?

Answer 19

1 / √n

Question 20

what does “n” represent ?

Answer 20

number

Question 21

in early september 2003, california’s governor gray davis approved a controversial law allowing people who were not legal residents to obtain a California state driver’s license. that week the California field poll released a survey showing that 59% of registered voters opposed the law and 34% supported it. this part of the survey was based on a random sample of just over 300 people.

what is the approximate margin of error for the field poll results ?

a) 3.33%
b) 5.77%
c) 59%
d) 34%

Answer 21

b) 5.77%

Question 22

how do you calculate the margin of error in the field poll study question ?

Answer 22

1 / √300 = 0.577 = 5.77%

Question 23

when calculating the margin of error how many decimal places do u move and in what direction ?

Answer 23

two spots to the right

Question 24

what is faster to collect? a smaple or a census ?

Answer 24

a sample is faster to collect than a census if the population is large

Question 25

what is a census ?

Answer 25

when you collect data form every single person or item in a population, not just a sample

Question 26

between a census and a sample, which includes everyone in order ot get a complete and accurate pictyre of the population ?

Answer 26

census

Question 27

define "probability sampling plans" :

Answer 27

everyone in the population has a specific chance of making it into the sample

Question 28

define "simple random sample":

Answer 28

every conceivable group of people of the required size has the same chance of being the selected sample

Question 29

what are the two things you need in simple random sampling ?

Answer 29

1) list of units in the population 2) source of random numbers (technology or table of random numbers)

Question 30

is sampling the first 100 students of a list ordered alphabetically an example of a simple random sample?

Answer 30

NO not an example of a simple random smaple

Question 31

when calculating the margin of error is "n" represented by the population or the sample ?

Answer 31

sample

Question 32

what are some sampling methods ?

Answer 32

- stratified random sampling - cluster sampling - systematic sampling - random digit dialing - multistage sampling

Question 33

what is stratified random sampling ?

Answer 33

when you divide population in groups (strata) and take a simple random sample from each

Question 34

what is the term used for when you divide a population into groups with similar traits (like age, gender, etc) and then randomly select samples from each group to ensure a fair representation ?

Answer 34

stratified sample

Question 35

what is a "strata" ?

Answer 35

plural for "stratum", meaning multiple subgroups within a population, each sharing a common characteristic

Question 36

what is a stratum ?

Answer 36

subgroup or category within a population that shared a common characteristic (age, gender, etc.)

Question 37

TRUE OR FALSE in stratified sampling, the population is divided into these strata before selecting samples from each one

Answer 37

TRUE

Question 38

what is cluster sampling ?

Answer 38

divide population into groups (clusters), take a random sample of clusters and measure all the units of selected clusters

Question 39

what is systematic sampling ?

Answer 39

divide population into as many consecutive segments as you need, randomly choose a starting point in the first segment, then sample at that same point in each segment

Question 40

what is an advantage to cluster sampling ?

Answer 40

need only a list of clusters, not a list of all individual units