Chapter 1

Question 1

generalization

Answer 1

only appropriate when based on samples that are:
-randomly selected or otherwise representative of a pop
-selected from that pop specifically

Question 2

confounding factors

Answer 2

factors that, when analyzing data, are hard to parse out if the cause is one, both/all, or none of them

Question 3

observational study

Answer 3

-taken w/o imposing treatments and a cause and effect canNOT be inferred
-observes characteristics of a sample and then generalizes to the pop
-does NOT determine who will be in what group

Question 4

experiment

Answer 4

-treatments are imposed and a cause and effect relation can be inferred
-a response variable behaves under differential conditions
-determines who will be in what group and what the experimental conditions will be like

Question 5

population characteristic

Answer 5

a # that describes the ENTIRE pop

Question 6

statistic

Answer 6

a # that describes a SAMPLE

Question 7

census

Answer 7

collects data from all individuals in a pop

Question 8

simple random sample

Answer 8

sample of size n is selected from the pop in a way that ensures that every different possible sample of the desired size has the same chance of being selected

Question 9

variable ‘n’

Answer 9

used to denote sample size; # of individual or objects in the sample

Question 10

sampling frame

Answer 10

a list of all individuals/objects in the sample

Question 11

sampling with replacment

Answer 11

sampling in which an individual/object, once selected, is put back into the sample before the next selection

Question 12

sampling without replacement

Answer 12

sampling in which an individual/object, once selected, is removed from the sample before the next selection

Question 13

when can you treat sampling with replacement as the same as sampling without replacement

Answer 13

when sample size ‘n’ is relatively small compared to the pop size (no more than 10% of pop)

Question 14

convenience sampling

Answer 14

selecting individuals/objects that are easy/convenient to sample

Question 15

voluntary response

Answer 15

a type of convenience sampling which relies solely on individuals volunteering to be part of a study (ppl motivated to respond are often HIGHLY motivated and respond with extremes)

Question 16

variable ‘N’

Answer 16

used to denote an entire population

Question 17

cluster random sample

Answer 17

when a pop is divided into cluster, and an simple random sample of clusters is taken, with all individuals within each cluster sampled
-grouping is ideally heterogeneous

Question 18

stratified random sample

Answer 18

pop is divided into strata based on a similar characteristic, with a simple random sample being taken with in each stratum and all selected individuals combined into larger sample
-strata are ideally homogeneous

Question 19

systematic random sample

Answer 19

randomly chose a start point, and the sample at a fixed periodic interval based off said start point
-aka 1-in-k systematic sample
-k=N/n

Question 20

variation

Answer 20

a measure of precision

Question 21

bias

Answer 21

the tendency for samples to differ from the corresponding pop in some systematic way

Question 22

undercoverage bias

Answer 22

when part of a pop has a reduced chance of being included in a sample

Question 23

voluntary response bias

Answer 23

occurs when an invitation is sent to all individuals in a pop to participate and those who choose to participate may differ from individuals who dont chose to participate

Question 24

question wording bias

Answer 24

when survey questions are confusing and/or leading

Question 25

self-reported response bias

Answer 25

when individuals inaccurately report their own traits (often happens in embarrassing or incriminating situations)

Question 26

selection bias

Answer 26

when samples are taken from a source where some groups are excluded

Question 27

measurement/response bias

Answer 27

when the method of observation tends to produce values that systematically differ from the true value in some way
-ex. improperly calibrated scale
-ex. wording in survey
-could occur from appearance/behaviors of those giving the survey

Question 28

when does an increase in sample size NOT reduce effects of bias in a study?

Answer 28

when selection method is flawed and when high nonresponse

Question 29

nonresponse bias

Answer 29

when responses are NOT obtained from all individuals selected for inclusion in the sample

Question 30

confounding variable

Answer 30

another variable that is related to the explanatory variable and influences the response variable
-may create a false perception of association

Question 31

what does a well designed experiment include?

Answer 31

1) comparison of 2+ treatment groups, with one control
2)random assignment/allotment of treatments to experimental units
3) replication
4) control of potential confounding variables, where appropriate

Question 32

single blind

Answer 32

where subjects in a study do NOT know which treatment they are receiving, but researches do (or vise-versa)

Question 33

double blind

Answer 33

neither subjects nor the researchers interacting with eh subjects are aware of the treatments being administered

Question 34

response variable

Answer 34

variable not controlled by experimenter, and is measured as part of the experiment

Question 35

explanatory variable

Answer 35

variables that have values that are controlled by the experimenters
(AKA factors)

Question 36

experimental conditions

Answer 36

any particular combination of the explanatory variables
(AKA treatments)

Question 37

experimental units

Answer 37

the smallest unit to which a treatment is applied
(AKA subjects)

Question 38

direct control

Answer 38

holding the other variables constant so that their effects are not confounded with those of the treatments

Question 39

replication

Answer 39

ensures that there is an adequate # of observations for each experimental condition

Question 40

statistical significance

Answer 40

that observed changes/differences occurred NOT merely by chance
-evidence that a treatment caused an effect

Question 41

variable ‘p’

Answer 41

the probability (chance) of observing a specific outcome due to chance variation
-how likely an outcome is to occur

Question 42

completely randomized design

Answer 42

an experiment in which experimental units are randomly assigned to treatments

Question 43

randomized block design

Answer 43

an experiment that incorporates blocking by dividing the experimental units into homogeneous blocks and then randomly assigning the individuals within each block

Question 44

control group

Answer 44

an experimental group that does NOT receive any treatment (AKA baseline)
-allows to assess how the response variable behaves when treatment is NOT used

Question 45

placebo

Answer 45

something that is identical to the treatment received, except it contains NO active ingredient(s)

Question 46

COMMON MISTAKES

Answer 46

1) drawing cause and effect from an observational study
2) generalizing results of an experiment that uses volunteers as subjects (only valid if provable that volunteers are representative)
3) generalizing data based on data from a poorly designed study
4) generalizing conclusions based on an study that used voluntary response/convenience sampling to a larger pop