apstats 4.2

Question 1

observational study

Answer 1

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

Question 2

experiment

Answer 2

statistical study where we do something to people, animals, or objects to observe the response

Question 3

explanatory variable

Answer 3

variable that may help, explain, predict, or cause changes in the response

Question 4

response variable

Answer 4

variable affected by the explanatory variable

Question 5

treatment

Answer 5

condition applied to variables

Question 6

factors

Answer 6

several explanatory variables

Question 7

experimental units

Answer 7

smallest collection of individuals to which treatments are applied

Question 8

subjects

Answer 8

human beings are called this

Question 9

cause and effect relationship

Answer 9

experiments are the only way we can have convincing evidence for this, an observational study cannot establish a cause and effect relationship

Question 10

confounding

Answer 10

when two variables are associated so that their effects on a response variable cannot be distinguished from each other

Question 11

when identifying a confounding variable

Answer 11

explain how the variable is associated with the explanatory variable, explain how the variable affects the response variable

Question 12

good experiment has these 4 components

Answer 12

comparison, random assignment, control, replication

Question 13

comparison

Answer 13

uses two or more treatments to compare response variables

Question 14

random assignment

Answer 14

experimental units are randomly assigned to treatments (method must be random using chance process, described specifically so people can recreate exactly)

Question 15

control

Answer 15

efforts made to keep other variables that might affect the response variable the same for all groups

Question 16

replication

Answer 16

more than one experimental unit in each group to tell the difference between effects of treatment and chance differences

Question 17

completely randomized design

Answer 17

experimental units are assigned to the treatments completely by chance

Question 18

control group

Answer 18

usually receives no treatment or an inactive treatment

Question 19

placebo

Answer 19

dummy pill that contains no active ingredients is used for a control group in dug trials

Question 20

placebo effect

Answer 20

subjects experiment improvement from a placebo

Question 21

blinding

Answer 21

do not tell subjects what they are receiving

Question 22

double-blinding

Answer 22

doctors and subjects are both unaware who is getting what

Question 23

statistically significant

Answer 23

an observed effect is so large that it would rarely occur by chance

Question 24

block

Answer 24

a group of experimental units in some way that is expected to affect the response to treatments

Question 25

randomized block design

Answer 25

separates the experimental units into blocks and then randomly assigns experimental units to treatments

Question 26

matched pairs design

Answer 26

matching pairs of similar experimental units into block sizes of 2