Chapter 4 Vocab in Russo's Bestest Period

Question 1

population

Answer 1

entire group of individuals we want information about

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 which we collect data

Question 4

sample survey

Answer 4

is a study that collects data from a sample that is chosen to represent a specific population

Question 5

convenience sampling

Answer 5

selects individuals from the population who are easy to reach

Question 6

bias

Answer 6

the study is designed in a way that is very likely to underestimate or very likely to overestimate the value you want to know

Question 7

voluntary response sampling

Answer 7

allows people to choose to be in the sample by responding to a general invitation (usually leads to the two extremes answering and thus bias overall)

Question 8

random sampling

Answer 8

involves using a chance process to determine which members of a population are included in the sample

Question 9

Simple Random Sampling (SRS)

Answer 9

of size (n) is chosen in such a way that every group of (n) individuals in the population has an equal chance to be selected as the sample

Question 10

Stratified Random Sample

Answer 10

selects a sample by choosing an SRS from each stratum and combining the SRSs into one overall sample

Question 11

Strata

Answer 11

are groups of individuals in a population who share characteristics thought to be associated with the variables being measured in the study

Question 12

cluster

Answer 12

a group of individuals in the population that are located near each other

Question 13

cluster sampling

Answer 13

selects a sample by randomly choosing clusters and including each member of the selected clusters in the sample

Question 14

undercoverage

Answer 14

occurs when some members of the population are less likely to be chosen or cannot be chosen in the sample

Question 15

nonresponse

Answer 15

occurs when an individual chosen for the sample can’t be contacted or refuses to participate

Question 16

response bias

Answer 16

occurs when there is a systematic pattern of inaccurate answers to a survey question

Question 17

observational study

Answer 17

observes individuals and measures variables of interest but does not attempt to influence the responses

Question 18

response variable

Answer 18

measures an outcome of a study

Question 19

explanatory variable

Answer 19

may help explain or predict changes in a response variable

Question 20

confounding

Answer 20

occurs when two or more variables are associated in such a way that their effects on a response variable can not be distinguished from each other

Question 21

experiment

Answer 21

deliberately imposes some treatment on individuals to measure their responses

Question 22

placebo

Answer 22

is a treatment that has no active ingredient, but is otherwise like other treatments (it an experiment has several explanatory variables, a treatment is a combination of specific values of these variables)

Question 23

treatment

Answer 23

a specific condition applied to the individuals in an experiment

Question 24

experimental unit

Answer 24

is the object to which a treatment is randomly assigned

Question 25

subjects

Answer 25

used when the experimental units are human

Question 26

factor

Answer 26

a variable that is manipulated and may cause a change in the response variable (i.e. 4 different types of food = food is 1 factor)

Question 27

levels

Answer 27

different values of a factor (i.e. 4 different types of food = 4 levels)

Question 28

control group

Answer 28

is used to provide a baseline for comparing the effects of other treatments sometimes the control group is given an inactive treatment (placebo), an active treatment, or no treatment

Question 29

placebo effect

Answer 29

describes the fact that some subjects in an experiment will respond favorably to any treatment, even if it is inactive

Question 30

double-blind experiment

Answer 30

Neither the subjects nor those who interact with them and measure the response variable know which treatment a subject received

Question 31

single-blind experiment

Answer 31

either the subjects don't know which treatment they are receiving or the people who interact with them and measure the response variable don't know which subjects are receiving which treatment

Question 32

random assignment

Answer 32

means that experimental units are assigned to treatments using a chance process

Question 33

control

Answer 33

means keeping other variables constant for all experiential units

Question 34

replication

Answer 34

means using enough experimental units to distinguish a difference in the effects of the treatments from chance variation due to the random assignment

Question 35

completely randomized design

Answer 35

the experimental units are assigned to the treatments completely by chance

Question 36

block

Answer 36

is a group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments

Question 37

randomized block design

Answer 37

the random assignment of experimental units to treatments is carried out separately within each block

Question 38

matched pairs design

Answer 38

is a common experimental design for comparing two treatments that use blocks of size 2 - in some matched pairs designs, two very similar experimental units are paired and the two treatments are randomly assigned within each pair - in others, each experimental unit receives both treatments in random order

Question 39

sampling variability

Answer 39

refers to the fact that different random samples of the same size from the same population produce different estimates

Question 40

population

Answer 40

the entire group of individuals we want information about