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Research Eval > Handout Review > Flashcards

Handout Review Flashcards

1
Q

The number of occurrences at ONE PARTICULAR TIME

A

Prevalence

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2
Q

The occurrence, RATE, or frequency of a disease

A

Incidence

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3
Q

???

A

Outlier

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4
Q

Represented by “r” (rho)

The closer to 1 (or -1) the stronger the relationship. Closer to 0? A weaker relationship.

Pearson correlation is the most common but sensitive to outliers (can be misleading if non-linear relationship)

A

Correlation coefficient

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5
Q

Measures magnitude of an association between an exposed and non-exposed (control) group

Calculated using cumulative incidence data to measure the probability of developing disease

A

Relative Risk

Must have incidence information (cohort of clinical trials are conducted over time)

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6
Q

Basic risk statements express the likelihood that a particular event will occur within a particular population

Identifies what in our environment can lead to beneficial or adverse medical outcomes

A

Relative risk

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7
Q

Proportion of people with the disease who have a positive test for the disease

A

Sensitivity

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8
Q

The ability of the test to identify correctly those who have the disease

A

sensitivity

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9
Q

The proportion of people without disease who have a negative test

A

specificity

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10
Q

Ability of the test to identify correctly those who don’t have the disease

A

specificity

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11
Q

In this screening, a less expensive/invasive/uncomfortable test is generally performed first… those that screen positive are recalled for further testing with more expensive/invasive/uncomfortable test

A

Two-stage (sequential) testing

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12
Q

Loss in net sensitivity, gain in net specificity

A

Two-stage (sequential) testing

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13
Q

Patient is considered positive if they test pos on either/both tests.

Pt considered negative if they test neg on both.

A

Simultaneous testing

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14
Q

Net gain in sensitivity, net loss in specificity

A

Simultaneous testing

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15
Q

ability to apply results obtained from a study population to a broader population

A

External validity

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16
Q

Also called generalizability

A

External validity

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17
Q

Within the confines of the study, the results appear to be accurate and the interpretation of the investigators is supported

A

Internal validity

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18
Q

Most valuable in determining the statistical significance of an effect estimate?

A

confidence interval

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19
Q

More important than p-value? A better determination of significance?

A

Confidence interval

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20
Q

Produces a range within which the true value most likely lies…

“We be 95% certain that the true value is within the __ range”

Narrower is better…

A

Confidence interval

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21
Q

Odds ratios calculated in a case-control study are a good approximation of relative risk in the population when what three conditions are met?

A

When cases studied are representative, with regard to history of exposure, of all people w/ the disease in the population from which the cases were drawn.

When CONTROLS studied are representative, with regard to history of exposure, of all people w/ the disease in the population from which the CONTROLS were drawn.

When the studied disease doesn’t occur frequently.

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22
Q

The number of patients who need to receive the new intervention instead of the standard alternative in order for ONE additional patient to benefit

A

number needed to treat (NNT)w

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23
Q

Expresses the likelihood of the tx to benefit an individual patient

A

number needed to treat (NNT)

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24
Q

Is there an absolute value for NNT that defines whether something is effective or not?

A

No. But NNTs for very effective treatments are usually in the range of 2-4.

Usually a lower number b/c we expect large effects in small numbers of people.

Larger NNTs can be found useful where few pts are affected in large populations (use for prophylactic measures)

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25
Q

When an experimental treatment is detrimental, what term would we employ?

A

number needed to harm (NNH)

Numbers are similar to NNT, except NNH will have a negative absolute risk reduction

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26
Q

Low probability of a false negative?

A

Sensitivity

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27
Q

Highly useful when negative because it rules out the disease

A

Sensitivity

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28
Q

Low probability of a false positive

A

specificity

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29
Q

Highly useful when it is positive because it tends to rule in the disease

A

Specificity

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30
Q

Means that subjects are analyzed according to the categories into which they were originally randomized.

Even if subjects withdraw/fail to take prescribed/otherwise adjust their tx, they still belong to their original tx group

A

Intention to treat analysis

note that this was taken from the book the definition couldn’t be found in the slides

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31
Q

Indicates the chance of a random error

A

p-value

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32
Q

P-value key metrics?

A

p = or < .05 (statistically significant)

p < .001 (HIGHLY significant)

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33
Q

When a drug/procedure/intervention works under ideal circumstances

A

efficacy

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34
Q

When we reject the null hypothesis, but the hypothesis is actually true?

A

Type 1 error

aka Alpha error

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35
Q

When we fail to reject the null hypothesis, but the null hypothesis is false

A

Type 2 error

aka Beta error

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36
Q

variables that correlate directly or indirectly with the dependent and independent variables

A

Confounding variables

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37
Q

AKA hidden variable, lurking variable

An extraneous variable in a statistical model that correlates (positively or negatively) with both the dependent and independent variable

A

confounding variable

38
Q

A descriptive study that provides a narrative in professional literature that IDs a single incident and discusses pertinent factors related to that patient

Brings a nove/unusual patient to the attention of colleagues

A

case report

39
Q

Descriptive study of individual cases that share a commonality

A

case series

40
Q

Case series are used to?

A

Examine adverse events/effects

Catalog new diseases/outbreaks

Determine feasibility/safety of new tx/intervention

Discuss potential efficacy of new tx

41
Q

An analytic/observational study

Studies in which pts who already have a specific condition are compared with people who do not have the condition

A

Case control studies

Researcher looks back to identify factors/exposures that might be associated with illness

42
Q

Tries to capture the cause and effect relationship by comparing frequency of a risk factor among those who are exposed and not exposed

A

Case-control studies

43
Q

thorough, comprehensive, and explicit way of interpreting the medical literature

A

systematic review

44
Q

STATISTICAL approach to combine the data derived from several seleted studies

A

meta-analysis

45
Q

identify a group of patients who are already taking a particulat tx/have an exposure, follow them forward over time and then compare their outcomes with a similar group that has not been affected by the treatment or exposure being studied

A

prospective cohort studies

46
Q

Strongest observational study?

A

cohort study

47
Q

Strengths of cohort study?

A

study multiple effects of a single exposure

identify a temporal relationship b/w exposure/outcome

help confirm casue/effect and magnitude of effect

can measure incidence of dz

can calculate relative risk

48
Q

Highest validity of observational study design?

A

Cohort study

49
Q

Cross sectional

A

An analytic, observational study

examines relationship between otucomes and other variables of interest as they exist in a defined population at one partcular time

50
Q

Can a cross-sectional determine prevalence?

A

Yes, but it cannot show causality nor a temporal relationship

51
Q

Cross sectional strengths/

A

assess multiple outcomes and exposures simultaneously

can be completed quickly

data generated can lead to further studies

can generate prevalence

52
Q

Cross sectional weaknesses?

A

no time reference (snapshot in time)

only useful for common conditions

cannot calculate incidence

Results are dependent on study population

53
Q

Main purpose of randomization is to?

A

prevent any potential biases on the part of the investigators

54
Q

Though randomization strives for comparability, it is not….?

A

guaranteed

55
Q

The gold standard?

A

Double blinded randomized control trial

56
Q

Limitations of control studies?

A

Large trials (may effect statistical power)

Long term follow up (possible losses)

Compliance

Expensive

Possible ethical questions

57
Q

Quasi experimental study aka?

A

non-randomized control trial

58
Q

Limitations of non-randomized control trials?

A

Study group characteristics may not be balanced at baseline and these differences may confoudn study’s results

(typical confounding variables include age, educational level, motivation, severity of illness, socioeconomic status/income, comorbidities)

59
Q

Variant of case-control study

Each case becomes their own individual control

Used for transient exposures during a discrete occurence?

A

Case crossover study

60
Q

Must have a washout period?

A

Case crossover study

61
Q

Intention to treat?

A

Analyzed according to original randomized assignment

If bias occurs, typically biases towards the null; provides a more conservative estimate

62
Q

Research dealing with phenomena that that are difficul or imposible to quantify mathematically, such as beliefs, meanings, attributes, and symbols; it may invovle content analysis

A

qualitative research

63
Q

Basic level: a descriptive account of the date

i.e., this is what was said but no comments or theories as to why or how

(regarding qualitative research)

A

manifest level

64
Q

higher level; a more interpretive analysis that is concerned with the response as well as what may have been implied or inferred

(regarding qualitative research)

A

Latent level

65
Q

the score that occurs most frequently

A

mode

Measure of central tendency

66
Q

middle point

A

median

Measure of central tendency

67
Q

the average

A

mean

Measure of central tendency

68
Q

least precise measure of central tendency?

A

mode

69
Q

percent of patients with positive test who actually have the disease

A

positive predictive value

70
Q

assesses reliability of positive test

A

positive predictive value

71
Q

Percentage of patients with a negative test who actually do NOT have the disease

A

negative predictive value

72
Q

assesses reliability of a negative test

A

negative predictive value

73
Q

If you have a low prevalence of disease, in regards to positive predictive value, you’ll have ___ PPV, your false positive ____, and its a ___ reliable positive test result

A

lower

increase

less

74
Q

If you have a low prevalence of disease, in regards to negative predictive value, you’ll have ___ NPV, your false negative ____, and its a ___ reliable negative test result

A

higher

decreased

more

75
Q

Summarizes the same kind of information sensitivity and specificity and can be used to calculate the probability of disease in a low prevalence setting.

A

Likelihood ratio (LR)

76
Q

provides indication of the test’s discriminatory power

A

Likelihood ratio (LR)

77
Q

Low prevalence = Less reliable positive test result; therefore, use ___

A

Likelihood ratio (LR)

78
Q

LR addresses ?

A

How much more likely are we to find that a test is positive among patients with disease compared with those without disease?

79
Q

A positive LR (LR+) is the ratio of the proportion of diseased people with a positive test result (sensitivity) to the proportion of non-diseased people with a positive result (1-specificity).

A

How good the test is at “Ruling in” disease!

80
Q

A negative LR (LR-) is the proportion of diseased people with a negative test result (1-sensitivity) divided by the proportion of non-diseased people with negative test results (specificity)

A

How good the test is at “Ruling out” disease

81
Q

Measures the strength of association between an exposure and disease

A

Odds ratio (OR)

82
Q

If exposure does not affect (either cause or protect from) disease, the OR is ~ 1
If the exposure is related to the disease, the OR > 1
If the exposure is protective against the disease, the OR < 1

A

Odds ratio (OR)

83
Q

strives for comparability of the different treatment groups; however, its not guaranteed

A

randomization

84
Q

the best approach in the design of a trial, and the critical element of ______ is the unpredictability of the next assignment

A

randomization

85
Q

occurs when relationships that exist for groups are assumed to also be true for individuals

A

ecological fallacy

type of bias

86
Q

“When investigators know the identity of case and comparison subjects and which exposures are risks, objectivity is put to a strenuous test”

A

Researcher bias

from book pg 47

87
Q

Searching medical records more thoroughly or questioning more diligently about exposure to medical asbestos in cases of fibrotic lung disease or about the consumption of artificial sweeteners among bladder patients…

an example of?

A

Researcher bias

from book pg 47

88
Q

Both are used for the development of Clinical Practice Guidelines (CPGs)?

A

Meta analysis

Systematic review

89
Q

What is the difference between a “systematic review” and a “meta-analysis”?

A

A “systematic review” is a thorough, comprehensive, and explicit way of interpreting the medical literature

A “meta-analysis” is a statistical approach to combine the data derived from several selected studies

90
Q

is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control health problems

A

epidemiology

91
Q

the branch of statistics that deals with data relating to living organisms

Using the tools of statistics to help answer pressing research questions in medicine, biology, and public health

A

biostatistics

Research Eval (9 decks)

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