Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

PH 304 Midterm > Intro to Epi > Flashcards

Intro to Epi Flashcards

1
Q

What is the difference between general epidemiology and clinical epidemiology?

A

Clinical epi makes predictions about individual patients by analyzing clinical events in a group of similar patients.

General epidemiology is the study of diseases and their consequences in populations, without a focus on predicting individual outcomes or clinical decision making.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the key premise of epidemiology (and life in general)?

A

life is uncertain

OoOoOh AaAaAah

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Name 4 uses of epidemiology.

A
  1. describe the distribution of disease
  2. test hypothesis
  3. Assess research reports
  4. Assess clinical and population data
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 4 D’s of treatment outcomes that are analyzed by epidemiological studies?

A

Death
Discomfort
Disability
Dissatisfaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do you best estimate the probability of an outcome in an individual patient?

A

by referring to past experiences with GROUPS of SIMILAR patients

i.e. not the last patient you saw, please and thank you

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the best study design to eliminate selection bias?

A

randomized controlled trial

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe a cohort/incidence study.

A

individuals in study population are classified into exposure categories.

Patients are followed and “outcome” is measured.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Are cohort studies retrospective or prospective?

A

Either!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

When are cohort studies most useful?

A

when the outcome is common and an RCT is too expensive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the best study method for rare outcomes?

A

Case control study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the best study method for common outcomes?

A

cohort studies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe a case control study

A

Choose 2 samples of individuals with and without the outcomes, then assess the exposure status some time in the past.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Does the ‘case’ v. ‘control’ classification in a case control study refer to exposure or outcomes?

A

outcomes!

classically, a case control study is retrospective so start with your outcome of interest.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the only kind of case control study that is not retrospective?

A

a nested case control study, in which the case and control subjects are drawn from a cohort study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is another term for a prevalence study?

A

a cross sectional study or survey

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe a cross-sectional study

A

the exposure and outcome are assessed at the same time (to assess prevalence)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the least expensive kind of study?

A

a prevalence/cross sectional study

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the main drawback of a cross sectional study?

A

because exposure and outcome are measured at the same time, there is no temporal relationship between the two

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Are sensitivity and specificity useful in analyzing data from a diagnostic or risk factor association study?

A

diagnostic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Are relative risk, hazard ratios and odds ratios useful for analyzing data from a diagnostic or a risk factor association study?

A

risk factor association - these statistics tell you about the association between a given risk factor and the outcome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Name 3 sampling methods

A

random
stratified random
convenience

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

“the degree to which the results of a study are correct for the sample of patients being studied.”

Does this describe internal or external validity?

A

internal validity - is your study describing the “truth” for the patients enrolled?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

“The degree to which the results of an observation hold true for patients who are not sampled.”

Does this describe internal or external validity?

A

External validity - is your study describing the “truth” for your patients who didn’t enroll?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the main threat to validity?

A

BIAS.

Is it just me or is the answer always bias?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the difference between bias and, for example, a single mistake made by a med student who stayed up late binge watching "pandemic"?
Bias is *systematic* - it undermines your entire data set in some kind of procedural way, not just the one data point.
26
Describe selection bias.
A systematic process which leads to the creation of a sample group which have other determinants for the outcome aside from the one you're studying.
27
What kind of bias is particularly prone to creating confounding variables?
selection bias - you create a second factor that "travels with" your outcome of interest and distorts your data
28
Define measurement bias.
Measurements that are imprecise and/or methods of measurement that vary between study groups
29
Why do we measure things in patients?
to classify patients into different risk and outcome groups
30
Race: white, hispanic, afro american etc. would be an example of which of the following measurement scales: 1. nominal 2. ordinal 3. interval
nominal Can also be dichotomous ( x versus y) nominal = nombre = names (yay spanish)
31
COVID positive v. COVID free is an example of which kind of measurement scale? 1. nominal 2. ordinal 3. interval
this is an example of a dichotomous nominal scale
32
"Age 15 to 24, 25 to 34, etc.' is an example of which kind of measurement scale? 1. nominal 2. ordinal 3. interval
ordinal - there's no inherent ranking or ordering * this is always confusing to me, because I think of age in years as being "ordered" since none of us just popped into the world at 25 years of age, but I think the idea is that none of these age categories create any kind of mathematical difference in your analysis - any participant could be in any category at the moment they enroll, and those categories do not need to be spanning the same number of years (e.g. age 65+ covers more years than 1 to 15, but we treat them the same way in our analysis) - it's just a bucket to categorize people into. If I'm thinking about this wrong lmk.
33
"The ounces of wine Alba had last night" is an example of which measurement scale? 1. nominal 2. ordinal 3. interval
interval - there's an inherent order and the interval between each ounce is equal because that's how physics works
34
What's the difference between a continuous or discrete variable?
continuous: 1.1, 1.12, 1.13 etc discrete: number of births (1, 2, 3, 4, etc). You can't have 1.10 births (though we haven't had repro-GU yet so idk for sure)
35
Central tendency and distribution can be applied to what kind of scale data? 1. nominal 2. interval 3. ordinal
interval
36
How do we assess error due to bias?
validity/accuracy (bias impacts validity, validity tells us about bias... validity = bias, bias = validity. You get the idea).
37
How do we assess error due to random chance?
reliability
38
Why do we compare things to our gold standard? (don't overthink this)
to know if our data is VALID
39
If you don't have a gold standard, what are two other aspects of your data that you can assess for bias?
content validity | construct validity
40
Define content validity
The extent to which the method of measurement includes all the relevant dimensions of a construct and nothing else. I.e. does our measurement include everything that is important to know about our outcome of interest?
41
Define construct validity
The extent to which the measurement predicts a directly observable phenomenon i.e does our measurement actually measure what we think it measures?
42
Does INTRArater reliability refers to the measurement instrument or the operator?
instrument
43
Does INTERrater validity refer to the measurement instrument or its operator?
operator
44
Define type I error
A false positive
45
Define type II error
A false negative
46
Define P value
estimates the probability that the observed effect IS due to chance, given the assumption that no association exists in your population BIG p value = Random chance is right
47
What is the difference between clinical and statistical significance?
Clinical significance is, essentially, a value judgment by providers and patients: What is WORTH accomplishing in a given intervention? Statistical significance is just telling you if something is due to chance, and is heavily impacted by a study's power.
48
What is power directly proportional to? (4)
1. sample size 2. type I error probability 3. size of effect 4. proportion of patients experiencing the outcome
49
What do confidence intervals assess?
the precision of an effect estimate
50
If a confidence interval excludes the no effect value, what is always true of the effect?
it is statistically significant and the p value is 0.05 or less
51
What is descriptive epidemiology?
exactly what it sounds like - it DESCRIBES who has what in which location at what time. Descriptive should make you think of prevalence and incidence
52
What is analytic epidemiology?
Epidemiology assessing the determinants of disease - think of cause and effect, risk factors, exposures, etc.
53
What kind of study method lacks a comparison group?
case reports/series
54
Define ecological fallacy.
When researchers reach conclusions on the relationship between an exposure and disease at the individual level based on ecological data, which is population based. eg. sour cream consumption correlates with motorcycle collision deaths
55
Is prevalence related to rates or proportions?
proportions - proportions compare subgroups to larger groups, without a component of time
56
is incidence related to rates or proportions?
rates - rates compare change over time
57
Give two (general) examples of a ratio.
a proportion and a rate
58
In a ratio, are the numerator and denominator always drawn from the same group?
not necessarily - you are comparing the number or rate of things in one group versus things in another group. A proportion and a rate are two specific examples of ratios in which the numerator is a sub group of the denominator
59
in a proportion, are the numerator and denominator drawn from the same group?
Yes! the numerator is a subset of the denominator
60
Is a 'proportionate mortality ratio' an example of a proportion or a rate?
A proportion: ex. 2020 COVID deaths in USA divided by all deaths in 2020 in the USA
61
Is a 'participant rate' a proportion or a rate?
proportion - number of individuals enrolled out of a pool of eligible individuals. There is no "time" component to the measurement in this instance. the lesson here should be that the name of the statistic is a LIE and cannot be trusted.
62
Are proportions or rates a measure of risk?
rates!
63
Is a mortality rate an example of a proportion or a rate?
A rate - it involves *time* number of deaths divided by the population over a specific time period
64
Define cumulative incidence
Number of new cases during specified period divided by size of population at start of time period
65
Define incidence rate
number of new cases during specified time interval divided by summed person-years of observation
66
What is different between incidence rate and cumulative incidence: the numerator or the denominator?
the denominator changes! Denominator for IR is the sum of each person's time under observation without disease, while in CI it is just the size of the population studied
67
What is one big advantage of incidence rate calculations?
Because person-time is calculated for each subject, it can accommodate persons coming into and leaving the study. It allows enrollees to enter the study at different times.
68
What is an important disadvantage in incidence rate calculations?
Person-time assumes that the probability of disease during the study period is constant, so that 10 persons followed for one year equals one person followed for 10 years. Because the risk of many chronic diseases increases with age, this assumption is often not valid.
69
"What is the risk that an individual will develop the disease over a given time interval?" does this describe incidence rate or cumulative incidence?
cumulative incidence
70
"How quickly or frequently does a disease occur in a population?" does this describe incidence rate or cumulative incidence?
incidence rate
71
What are the 3 assumptions that must be met for "incidence x duration = prevalance"?
1. incidence must be constant 2. average duration of disease is constant 3. prevalence in population is low
72
What is the main difference between a crude/category specific rate and an adjusted rate?
Adjusted rates are comparisons between two populations and ARE NOT REAL NUMBERS Crude rates describe actual cases and events in a population
73
how are crude rates and category specific rates related?
Crude rates are a weighted average of the individual category-specific rates. The weights are the proportion of the population in that category
74
When do you use the direct method of age adjustment?
Use direct method when you know the age specific rates and a standard population is available
75
When do you use indirect method for age adjustment?
Use indirect method when the age-specific rates are unknown or unstable (small numbers)
76
How should external standards be used in age adjustment?
You need to use the same external standard on all the populations being studied so that you have a valid comparison point between the two you should always report what your standard population is
77
When should direct age adjustment NOT be used?
`. if the category specific rates are not available OR the number of cases is less than 20
78
How do I calculate an indirect age adjustment?
Multiply my STANDARD age category rates by the people in each age category of my STUDY population = expected numbers in my study population Then look at my actual study results - do they match the expected numbers i.e. what's the standardized mortality ratio (SMR)
79
How do I calculate direct age adjustment?
Multiply my STUDY age specific rates by the number of individuals in my STANDARD age categories = this tells me what my study results would have looked like in a population without a weighted average skewed by age
80
What is the SMR?
number of observed deaths/number of expected deaths Expected deaths are calculated by indirect age adjustment
81
Does surveillance include controlling the problem?
nope - you're just compiling information so that the people controlling the issue have good information as to what is happening
82
Define syndromic surveillance
surveillance which focuses on less specific criteria (i.e. people with a self reported fever, as opposed to cases of clinically confirmed fevers)
83
Define active notification in surveillance
Organization conducting surveillance initiates procedures to obtain reports of health event
84
Define passive notification in surveillance
Organization conducting the surveillance does not contact reporters but rather leaves the initiative for reporting health event to providers
85
Define sentinel notification in surveillance
Organization conducting surveillance relies on pre- arranged sample of reporters who agreed to report cases of health event
86
Describe a point source outbreak with index case and limited spread
More and more people get infected then dies down after a peak
87
Describe an index case with propagated spread
Index case or cases --> handful of cases --> then more --> then propagates as it goes on --> only goes away once you identify and control it (or can go away on its own when it loses its hosts) (ie. COVID)
88
What are two types of study methods that are used to formulate a hypothesis during an outbreak investigation?
cohort and case control studies

PH 304 Midterm (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions