Sampling and Surveys Vocab

Question 1

population

Answer 1

all of the individuals from whom we want data

Question 2

census

Answer 2

collects data from every individual in the population

Question 3

sample

Answer 3

a subset of individuals in the population from where we collect data

Question 4

sample survey

Answer 4

stidy collecting data from a sample of the population.

1) decide population
2) find what want to measure
3) choose how pick sample

Question 5

convenience sampling

Answer 5

selects individuals who are easy to reach

Question 6

Issues with convenience sampling

Answer 6

1) undercoverage
2) response bias (who is asking influence)
3) nonresponse bias

Question 7

bias

Answer 7

a method that systematically favors certain outcomes over another

Question 8

Voluntary response sampling

Answer 8

participants voluntarily chose to join the sample

Question 9

Issues with voluntary response sampling

Answer 9

1) voluntary response bias (could have strong opinions)
2) undercoverage
3) non response bias

Question 10

Random Sampling

Answer 10

Uses chance to determine who is included in the data set

Question 11

Simple Random Sampling

Answer 11

Every group of n individuals has an equal chance of being selected (ideal)

Question 12

Issues with SRS

Answer 12

1) non response bias
2) most ideal
3) hard to conduct

Question 13

How to phrase SRS

Answer 13

Randomly assign [subject] numbers [1-3000]. Use a random number generator to select [100] people, ignoring repeats.

menu-probability-randseed; menu-prob-randint(lower, upper, trials)

Question 14

Sampling without replacement

Answer 14

Once an individual is selected, they can not be selected again

Question 15

strata

Answer 15

groups of people who share characteristics thought to be associated with tested variable

Question 16

Stratified Random Sampling

Answer 16

Divide population into strata and combine subsamples

Question 17

Issues with Stratified Random Sampling

Answer 17

1) non response

2) very hard to conduct/time consuming

Question 18

How to phrase Stratified Random Sample

Answer 18

Stratify by [group]. Randomly assign [subject] numbers [1-3000]. Use a random number generator to select numbers [25] from each [group].

Groups of blubber fish 20-move down 20 on 0.25-0.5cm and get fish #37.

Question 19

cluster

Answer 19

group of individuals in a population that are near each other

Question 20

cluster sampling

Answer 20

Select sample by randomly choosing clusters

Question 21

How to phrase cluster

Answer 21

Randomly select [5] [group] and survey every [subject] in those [groups]

Question 22

Issues with cluster sampling

Answer 22

1) undercoverage

2) nonresponse

Question 23

Systematic Random Sampling

Answer 23

chose every [10th] seat in a group of [800] for a sample size of [80].

Question 24

How to phrase Systematic Random sampling

Answer 24

Randomly assign [subject] numbers [1-3000]. Use a random number generator to select numbers [1-10]. Survey every [30th] [subject].

Question 25

Issues with Systematic Random sampling

Answer 25

1) non response | 2) time consuming

Question 26

undercoverage

Answer 26

part of the population is not accounted for in the sampling

Question 27

non response

Answer 27

individual refuses to participate or can not be contacted

Question 28

response bias

Answer 28

systematic pattern of inaccurate responses (based on interviewer, or voluntary response)

Question 29

observational study

Answer 29

observes individuals and measures variables without influencing results. Only confirms correlation, not causation. Ex: smoking, volcano, natural

Question 30

response variable

Answer 30

measures outcome of a study

Question 31

experimental study

Answer 31

Experimenter controls variables. Can show causation.

Question 32

explanatory variable

Answer 32

helps explain or predict changes in response variable (x)

Question 33

confounding

Answer 33

variable influences independent and dependent variables (extra variable other than what testing for).

Question 34

experiment

Answer 34

imposes treatments on individuals and compares with a control group to measure impact.

Question 35

placebo

Answer 35

treatment without any active ingredient (control)

Question 36

treatment

Answer 36

specific condition applied to individuals in a experiment

Question 37

experimental unit

Answer 37

object treatment is randomly assigned

Question 38

subject

Answer 38

word for when experimental unit is a human being

Question 39

factor

Answer 39

An explanatory variable that is manipulated and may lead to a change in response variable

Question 40

level

Answer 40

the degree to which the explanatory variable has changed (0.5ga, 1ga, 2ga)

Question 41

control group

Answer 41

baseline to compare effects of other treatments. Could be a placebo, active treatment, or no treatment

Question 42

placebo effect

Answer 42

belief that react to treatment, even when received inactive treatment (unknowingly).

Question 43

double-blind

Answer 43

neither subject nor administrator know what the variables are/ if it is a placebo

Question 44

single blind

Answer 44

either the participant or the administrator knows the variables/ if it is a placebo

Question 45

Random assignment

Answer 45

experimental units are assigned treatments by chance

Question 46

control

Answer 46

keep all other variables constant in experiment

Question 47

replication

Answer 47

Ensuring a large sample size so that differences between treatment groups can be observed

Question 48

completely randomized design

Answer 48

sizes of groups, treatment received, and response variables completely random

Question 49

block

Answer 49

group of participants that are known to be similar (found after decide sample)

Question 50

randomized block design

Answer 50

random assignment of treatments to participants is decided within each block

Question 51

matched pairs design (2 students for each block)

Answer 51

Subjects similar characteristics selected into pairs (similar SAT score both take math test dif locations and compare)

Question 52

matched pairs design (student serves as own block)

Answer 52

Subjects similar characteristics selected into pairs (each student takes test twice, one in each location)

Question 53

sampling variability

Answer 53

random samples produce different estimates (larger= more accurate)

Question 54

statistically significant

Answer 54

When results cant be explained by chance alone. Only study that can draw conclusions from.

Question 55

scope of inference

Answer 55

1) random selection individ allow inference about population | 2) random assignment of individuals to groups allows inference cause and effect