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Elementary Statistics > Exam 1 Definitions > Flashcards

Exam 1 Definitions Flashcards

1
Q

Observational study

A

observes individuals, there is no treatment applied.

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2
Q

Experiment

A

imposes a treatment followed with observation

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3
Q

SRS

A

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

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4
Q

Multistage sample

A

stratify the population then randomly choose a sample from each strata

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5
Q

Stratified random sample

A

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

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6
Q

Block design

A

collect individuals in groups by similar characteristics ??

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7
Q

Matched pairs

A

a block design with two treatments for each individual

or an equally matched pair with random selection for treatment.

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8
Q

Voluntary response

A

Sample taken from people that chose themselves to respond

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9
Q

double-blind experiment

A

Neither facilitator nor subject know what treatment is being applied

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10
Q

factor

A

explanatory variable

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11
Q

confounding

A

lurking variable that confuses ??

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12
Q

bias

A

systematic errors in the way the sample represents the population

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13
Q

lurking variable

A

variable not in study, but has an effect

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14
Q

Informed consent

A

subjects give permission to collect and use data

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15
Q

convenience sampling

A

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

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16
Q

sampling design

A

how samples are collected

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17
Q

inference

A

process of drawing conclusions about a population from a sample

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18
Q

undercoverage

A

groups in the population but not in the sampling process

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19
Q

nonresponse

A

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

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20
Q

response bias

A

inaccurate responses due to dishonesty, embarrassment, confusion

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21
Q

wording bias

A

confusing or misleading questions

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22
Q

treatment

A

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

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23
Q

randomized comparative experiment

A

comparison of treatments where subjects are assigned randomly to the treatments

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24
Q

Simple random sample (SRS)

A

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

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25
Q

Bias

A

systematic errors in the way the sample represents the population

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26
Q

Failure to use random sampling results in ___.

A

bias

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27
Q

What samples are prone to a large bias?

A

Voluntary response bias

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28
Q

Most national surveys are carried out how?

A

by phone using random digit sampling

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29
Q

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

A

disturbing

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30
Q

Experiment

A

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

31
Q

Purpose of an Experiment is …

A

to study whether the treatment causes a change in the response

32
Q

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

A

Observational study

33
Q

Variable are confounded when:

A

A. their effects on a response cannot be distinguished from each other.

B. lurking variables cause changes in the response

34
Q

Treatment

A

combination of values of the explanatory variables (factors)

35
Q

Experiment design involves

A
  1. control & randomization to combat bias

2. using enough subjects to reduce chance variation

36
Q

simplest control

A

comparison of two treatments on same subject

37
Q

Randomization should be used to produce …

A

2 similar treatment groups

38
Q

Double blind experiment

A

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.

39
Q

Blocks of similar individuals

A

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

40
Q

Matched pairs

A

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

41
Q

All human ______ raise _____ questions

A

endeavors

ethical

42
Q

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

A

data

conclusions

43
Q

The most complex ethical situation is when …

A

Treatments are imposed on people

44
Q

IRB-institutional review board

A

reviews all planned studies in advance.

It is charged with protecting safety and well-being of subjects.

45
Q

Informed consent is given

A

before subjects participate in an experiment

46
Q

Individual data is kept ____.

A

confidential

47
Q

Randomized comparative experiments are

A

only way to see true effects of new treatments

48
Q

Clinical trials produce great benefits but …

A
  • most benefits go to future patients

* risks are borne by subjects of trial

49
Q

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

A

interests

prevail

50
Q

Data set

A

contains info on individuals

51
Q

variables

A

describe some characteristic of an individual

52
Q

categorical variable

A

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

53
Q

quantitative variable

A

numerical value measuring some characteristic

54
Q

Exploratory data analysis

A

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

55
Q

Distribution

A

the values a variable takes and how often it takes them

56
Q

Pie charts and bar graphs are examples of

A

categorical variable distributions

57
Q

Histograms and Stemplots

A

show quantitative variable distributions

58
Q

Outliers

A

observations that lie outside the overall pattern of a distribution

59
Q

A numerical summary of a distribution should

A

report the center and its spread

60
Q

mean describes _______

Median describes _______

A

arithmetic average of the observations

midpoint of values

61
Q

5 number summary consists of

A

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

62
Q

Boxplots

A

useful for comparing several distributions.

based on 5 number summary

63
Q

variance and standard deviation measure

A

the spread about the mean

64
Q

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

A

Resistant measure

65
Q

An example of a resistant measure:

A

Median and quartiles

66
Q

Normal distributions show

A

symmetry & no outliers

67
Q

4 steps to organize problem

A
  1. state problem
  2. plan
  3. solve
  4. conclude
68
Q

Measures of central tendency

A

Mean
Median
Mode

69
Q

Measures of dispersion

A

range
interquartile range
variance & standard deviation
coefficient of variation

70
Q

Statistical calculations extrapolate from _______.

A

sample to population

71
Q

Statistical calculations can do:

A

Statistical estimation
Statistical hypothesis testing
Statistical modeling

72
Q

Statistical calculation cannot do:

A

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

73
Q

Statistical reasoning cannot help with these problems

A

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

74
Q

Statistics is at the ______ of mathematics and _____.

A

interface

science

Elementary Statistics (1 decks)

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