Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Epidemiology > Second midterm content > Flashcards

Second midterm content Flashcards

(82 cards)

Start Studying
1
Q

descriptive statistics vs inferential statistics

A

descriptive: used to describe the main features of a data set
inferential: used to draw conclusions and involve making inferences about the larger group from a smaller subset

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

measures of tendency vs measures of dispersion

A

tendency: mean, median and mode
dispersion: range. interquartile range and standard deviation

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

what is the central limit theorem

A

sampled means will tend to be normally distributed given that we took enough samples
- even If the data itself id not normal the CLT tells us that the distribution of the sampled means will be

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

what is a P value

A

the probability of obtaining the observed results assuming the null hypothesis is true
- if the p-value is less than the alpha value, the result is statistically significant

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

what is a T-test

A
  • compares the means of 2 groups
  • used when you have a continuous variable
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is an ANOVA test

A
  • compares the means of 3 or more groups
  • used when you have a continuous variable
  • won’t tell you which groups are different but will tell any of the groups are significantly different
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is a chi-squared test

A
  • determines if there is a relationship between 2 categorical variables
  • use when you are dealing with types of groups and want to know is one category is related to another
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is a Pearson correlation test

A
  • assesses the association between 2 continuous variables
  • use wan you want to determine the direction and strength of a relationship between 2 continuous variables
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is regression

A

shows how much the dependent variable will change when the independent variable is changed

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

types of regression

A

linear regression: models outcomes of continuous variables
polynomial regression: measures continuous variables with a non-linear relationship
logistic regression: model binary outcomes (either yes or no)

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

what is multiple linear regression

A

when the outcome is dependent on more than one variable

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

what do the measures of association and measures of effect measure

A

MoA: the ratio of 2 measures of disease frequency - null value is 1
MoE: the difference between 2 measures of disease frequency - null value is 0

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

what are the measures of association

A

risk ratio
odds ratio
incidence rate ratio

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

what are the measure of effect

A

risk difference
attributable proportion (exposed)
population attributable risk
population attributable fraction

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

what is risk ratio

A

compares the risk of getting disease in the exposed and not exposed group

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

what is odds ratio

A

measures the odds that an outcome will occur if exposed, compared to the odds of the outcome occurring if not exposed

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

confidence interval for measures of association

A

if the confidence interval includes 1 the association is not statistically significant

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

what is incidence rate ratio

A

the ratio of disease incident rate in the exposed group vs in the non-exposed group

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

what are person-time years

A

allows you to account for the individual time that each participant contributes

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

interpreting MoA

A

range = 0 to infinity
MoA = 1 means risk/odds/rate in exposed is equal to non exposed
MoA > 1 means greater in exposed individuals
MoA < 1 means less in exposed individuals

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

what is the case for risk ratio and odds ratio in rare diseases

A

RR ~ OR because a and c values are so small

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

what are measures of effect useful for

A

knowing how much disease could be eliminated by removing the exposure

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

what are measures of association useful for

A

investigating causation

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

what is baseline risk

A

disease in the non-exposed group OR amount of disease present not due to the exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what do measures of effect tell us about exposed groups
how mush od the total risk of disease is actually due to the exposure of interest
26
what is risk/rate difference
the difference in risk or rate of the outcome in the exposed and non-exposed groups
27
interpretation of risk/rate difference
the excess risk of getting disease due to exposure is...
28
what is excess risk
extra risk beyond the baseline risk
29
what is attributable proportion
the proportion of risk/rate of the outcome in the exposed group that is due to the exposure
30
interpretation of attributable proportion
...% of disease in the exposure group is due to the exposure
31
measures of effects in exposed groups vs in population
exposed groups: risk difference and attributable proportion populations: population attributable risk, population attributable fraction
32
what is population attributable risk
the amount of disease in the entire population that is due to the exposure prevalence of disease in population - baseline level of disease
33
interpreting MoE
range = -infinity to infinity MoE = 0: exposure has no effect MoE > 0: exposure positively associated with disease MoE < 0: exposure negatively associated with disease - null value is 0 because it is a difference not a ratio
34
population attributable fraction
proportion of disease in the entire population that is due to the exposure PAR/prevalence of disease in population
35
interpreting population attributable fraction
...% of disease in the population could be eliminated if the exposure was removed
36
interpreting population attributable risk
the excess risk of disease in the population that is due to the exposure is...%
37
inductive vs deductive research
inductive: observations deductive: intervening
38
what is quantitative research
- objective - one truth - observer doesn't influence findings - facts separated from values
39
what is qualitative reasearch
- subjective - truth is subjective perception of findings - findings are mutually created between observer and subject - value lead
40
types of qualitative research methods
interview focus group ethnographic research case study research record keeping qualitative observation
41
types of descriptive studies
case reports case series surveys
42
analytical vs descriptive studies
descriptive - provide information about occurrence of disease without investigating associations - generate hypothesis analytical - establish relationships between risk factors and the occurrence of disease, make comparisons between groups - hypothesis testing
43
types of analytical studies
observational studies experimental studies
44
what is an observational study
researcher has NO control over subjects being compared exposed subjects already exist
45
what is an experimental study
researcher randomly allocates subjects to the groups being compared and intervened (adds exposure)
46
when would you choose an observational study over an experimental study
if exposure of interest is harmful if it is expensive to administer exposure if the exposure is hard to control
47
types of observational studies
cross-sectional cohort case-control
48
what is a cross-sectional study
- select participants without regard to exposure or outcome status - then measure the exposure and outcome at the same time (a snapshot)
49
objective of cross-sectional studies
to estimate prevalence - how many subjects have exposure and how many have outcome?
50
prevalence vs incidence
prevalence: new and old cases (have the outcome) incidence: new cases (get the outcome)
51
why can we only measure prevalence and not incidence in cross-sectional studies
- because we cannot establish temporality since we determine E and O at the same time - exception = longitudinal studies
52
what are longitudinal studies (cross-sectional)
the same individuals are measured more than once, allows to establish incidence
53
advantages of cross-sectional studies
- determine prevalence of E and O - study multiple exposures and multiple outcomes - good for studying permanent factors - no loss-to-follow up selection bias - less potential for bias than case-control studies - can measure ALL MoA and MoE EXCEPT for rate
54
disadvantages of cross-sectional studies
- not good for rare E, rare O or short duration diseases - doesn't measure incidence, ant establish temporal sequence - selection, information and confounding bias
55
what is a cohort study
select participants based on exposure status
56
what is a cohort
a group of subjects that has a defined characteristic in common - exposure status
57
general design of cohort studies
- choose a group of disease free individuals - classify them based on exposure - follow over a time period - compare the development of disease in E+ and E- group
58
retrospective vs prospective cohort studies
retrospective: establish from past records and follow-up to present day or more past records proscpective: start from present day and follow into the future
59
Analysis in cohort studies
- measures incidence (new cases) - can use ALL MoE and MoA
60
advantages of cohort studies
- good for rare exposures - study several outcomes - temporal sequence established in prospective studies - provides incidence data - no recall-bias with prospective studies
61
disadvantages of cohort studies
- bad for rare outcomes - can study only one or a few exposures - selection, information and confounding bias - expensive and time consuming - can have long follow up time: loss to follow-up is a major concern and non-response bias
62
addressing confounding bias in cohort studies
exclusion/restriction: subjects have same level of major CFV matching: E- have same CFVs as E+ analytical citron: control for CFVs with stratification or multivariable regression
63
ways to ensure validity in in cohort studies
- selection of E+ and E- groups - follow-up of cohorts - objective diagnosis of disease status
64
how can we have more than 2 exposure groups in cohort studies
can have multiple E- groups or E+ groups with different levels of exposure
65
what is the biggest challenge in cohort studies
follow-up
66
what is a case control study
choose participants based on their disease status
67
what are cases and what are controls
cases: have the disease/outcome of interest controls: do not have the disease/outcome of interest - selection occurs at this level - determine who was exposed and who wasn't in both groups
68
why are case-control studies always retrospective
cases have already occurred do we must trace back if they were exposed or not
69
analysis of case-control studies
compare proportion of exposure in the cases with that in the controls - CANNOT calculate incidence/risk therefore NO RR, but can still calculate OR
70
advantages of case-control studies
- fast and inexpensive (because retrospective) - best for investigating source of an outbreak - good for rare diseases/outcomes - good for multiple risk factors for a single disease
71
disadvantages of case-control studies
- CAN'T calculate disease incidence or prevalence - can only study one outcome - study design most prone to all biases - bad for rare exposure - temporal relationship is an issue if using prevalent cases
72
what is a study base (case-control studies)
the population from which cases (and controls) are obtained primary study base: the population from which the cases arise can be easily defined secondary study base: one or more steps removed from the primary population
73
control selection from a secondary study base
- controls should be randomly selected from non-cases in the registry - those controls should be selected from diagnostic categories not associated with the exposure of interest
74
use of multiple controls in a case-control study
controls come from different sourced e.g. hospital and neighbourhood controls
75
why can't we calculate risk/rate ratio in case-control studies
because we set the risk of our disease by selecting participants based on their disease status - must use OR to estimate RR because OR ~RR for rare diseases
76
factors for evaluating studies (critical appraisal)
Methodological: study design, statistical analysis, addressing bias Non-methodological: relevance, originality, conflicts or interest
77
how to estimate PAF and AP in case-control studies
AP = (OR-1)/OR PAF
78
Recall bias in case-control studies
- big problem if accuracy differs between cases and controls - retrospective so need to ask people about their past
79
how to ensure validity in case-control studies
- proper selection of cases and controls, to boost power can pick 4:1 controls:cases - ensure comparability - unbiased history of exposure to the factor of interest - control for confounding
80
what is critical appraisal
a systematic process used to identify the strengths and weaknesses of a research article in order to assess the usefulness and validity of research findings - lacks a "gold standard"
81
questions asked in critical appraisal (10)
relevance? adds something new? what is the research question? appropriate study design? addresses bias? performed as per methods stated? hypothesis stated? appropriate stats used? justified conclusions? conflicts of interest?
82
what is the difference between the 3 types of observational studies
the way that participants are selected

Epidemiology (3 decks)

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