Exam 1 Definitions

Question 1

Observational study

Answer 1

observes individuals, there is no treatment applied.

Question 2

Experiment

Answer 2

imposes a treatment followed with observation

Question 3

SRS

Answer 3

sample chosen randomly to avoid bias, uses the laws of probability

Question 4

Multistage sample

Answer 4

stratify the population then randomly choose a sample from each strata

Question 5

Stratified random sample

Answer 5

divide into strata by similarity of individuals then apply simple random selection to pick a sample from each strata

Question 6

Block design

Answer 6

collect individuals in groups by similar characteristics ??

Question 7

Matched pairs

Answer 7

a block design with two treatments for each individual

or an equally matched pair with random selection for treatment.

Question 8

Voluntary response

Answer 8

Sample taken from people that chose themselves to respond

Question 9

double-blind experiment

Answer 9

Neither facilitator nor subject know what treatment is being applied

Question 10

factor

Answer 10

explanatory variable

Question 11

confounding

Answer 11

lurking variable that confuses ??

Question 12

bias

Answer 12

systematic errors in the way the sample represents the population

Question 13

lurking variable

Answer 13

variable not in study, but has an effect

Question 14

Informed consent

Answer 14

subjects give permission to collect and use data

Question 15

convenience sampling

Answer 15

sample collected by taking members of population that are easiest to reach

Question 16

sampling design

Answer 16

how samples are collected

Question 17

inference

Answer 17

process of drawing conclusions about a population from a sample

Question 18

undercoverage

Answer 18

groups in the population but not in the sampling process

Question 19

nonresponse

Answer 19

the individual chosen can’t be contacted or refuses to participate

Question 20

response bias

Answer 20

inaccurate responses due to dishonesty, embarrassment, confusion

Question 21

wording bias

Answer 21

confusing or misleading questions

Question 22

treatment

Answer 22

experimental condition applied to subjects, each treatment being a combination of values of the explanatory values

Question 23

randomized comparative experiment

Answer 23

comparison of treatments where subjects are assigned randomly to the treatments

Question 24

Simple random sample (SRS)

Answer 24

basic sampling design where every possible sample has the same chance to be chosen

Question 25

Bias

Answer 25

systematic errors in the way the sample represents the population

Question 26

Failure to use random sampling results in ___.

Answer 26

bias

Question 27

What samples are prone to a large bias?

Answer 27

Voluntary response bias

Question 28

Most national surveys are carried out how?

Answer 28

by phone using random digit sampling

Question 29

A sample survey will gather information about a population without _______ during the process.

Answer 29

disturbing

Question 30

Experiment

Answer 30

not observational, it imposes a treatment in order to observe the response

Question 31

Purpose of an Experiment is ...

Answer 31

to study whether the treatment causes a change in the response

Question 32

Which kind of study is a terrible way to gauge the effect of a treatment?

Answer 32

Observational study

Question 33

Variable are confounded when:

Answer 33

A. their effects on a response cannot be distinguished from each other. B. lurking variables cause changes in the response

Question 34

Treatment

Answer 34

combination of values of the explanatory variables (factors)

Question 35

Experiment design involves

Answer 35

1. control & randomization to combat bias | 2. using enough subjects to reduce chance variation

Question 36

simplest control

Answer 36

comparison of two treatments on same subject

Question 37

Randomization should be used to produce ...

Answer 37

2 similar treatment groups

Question 38

Double blind experiment

Answer 38

uses a placebo to make lack of treatment realistic to control group plus the mediator doesn't know which group receives the treatment and which receives the placebo.

Question 39

Blocks of similar individuals

Answer 39

can be used as a form of control, randomly assign individuals from blocks to treatment group

Question 40

Matched pairs

Answer 40

Two similar individuals make a pair. Each subject in a pair receives one of the treatments.

Question 41

All human ______ raise _____ questions

Answer 41

endeavors | ethical

Question 42

When ___ is lacking it tends to make authors' _____ look stronger than it should.

Answer 42

data | conclusions

Question 43

The most complex ethical situation is when ...

Answer 43

Treatments are imposed on people

Question 44

IRB-institutional review board

Answer 44

reviews all planned studies in advance. | It is charged with protecting safety and well-being of subjects.

Question 45

Informed consent is given

Answer 45

before subjects participate in an experiment

Question 46

Individual data is kept ____.

Answer 46

confidential

Question 47

Randomized comparative experiments are

Answer 47

only way to see true effects of new treatments

Question 48

Clinical trials produce great benefits but ...

Answer 48

* most benefits go to future patients | * risks are borne by subjects of trial

Question 49

The _____of the subject must always _____ over that of science and society

Answer 49

interests | prevail

Question 50

Data set

Answer 50

contains info on individuals

Question 51

variables

Answer 51

describe some characteristic of an individual

Question 52

categorical variable

Answer 52

characteristic that separates each individual into a specific category, like gender

Question 53

quantitative variable

Answer 53

numerical value measuring some characteristic

Question 54

Exploratory data analysis

Answer 54

graphs & numerical summaries to describe variables in a data set & relations among them

Question 55

Distribution

Answer 55

the values a variable takes and how often it takes them

Question 56

Pie charts and bar graphs are examples of

Answer 56

categorical variable distributions

Question 57

Histograms and Stemplots

Answer 57

show quantitative variable distributions

Question 58

Outliers

Answer 58

observations that lie outside the overall pattern of a distribution

Question 59

A numerical summary of a distribution should

Answer 59

report the center and its spread

Question 60

mean describes _______ | Median describes _______

Answer 60

arithmetic average of the observations | midpoint of values

Question 61

5 number summary consists of

Answer 61

median, 1st and 3rd quartiles, minimum, max

Question 62

Boxplots

Answer 62

useful for comparing several distributions. | based on 5 number summary

Question 63

variance and standard deviation measure

Answer 63

the spread about the mean

Question 64

Any aspect of a distribution that is unaffected by the size of a population

Answer 64

Resistant measure

Question 65

An example of a resistant measure:

Answer 65

Median and quartiles

Question 66

Normal distributions show

Answer 66

symmetry & no outliers

Question 67

4 steps to organize problem

Answer 67

1. state problem 2. plan 3. solve 4. conclude

Question 68

Measures of central tendency

Answer 68

Mean Median Mode

Question 69

Measures of dispersion

Answer 69

range interquartile range variance & standard deviation coefficient of variation

Question 70

Statistical calculations extrapolate from _______.

Answer 70

sample to population

Question 71

Statistical calculations can do:

Answer 71

Statistical estimation Statistical hypothesis testing Statistical modeling

Question 72

Statistical calculation cannot do:

Answer 72

Define a population Randomly select a sample of subjects Randomly select treatment groups Measure a single variable in each subject

Question 73

Statistical reasoning cannot help with these problems

Answer 73

Population you care about is more diverse than population sampled You collect from a "convenience sample" rather than from a random sample Measurements may be incorrect, and assays may measure wrong thing You need to combine different measurements

Question 74

Statistics is at the ______ of mathematics and _____.

Answer 74

interface | science