Exam 2 Review Session

Question 1

What is the method of difference in epidemiological research?

Answer 1

*A situation where all factors in two or more domains are the same except for a single factor
*e.g: Differences in coronary heart disease rates are due to differences in physical activity levels.

It helps identify causative factors by comparing different scenarios.

Question 2

A cohort study differs from a
case-control study in that:

Answer 2

Subjects are enrolled or categorized on the
basis of their exposure status in a cohort study
but not in a case-control study

Question 3

What is the method of concomitant variation in epidemilogical research?

Answer 3

refers to a type of association in which the frequency of an outcome increases with the frequency of exposure to a factor.
*e.g:The greater number of cigarettes smoked, the higher mortality levels of lung cancer.

Question 4

What is the theory step in epidemilogic research defined as?

Answer 4

General accounts of causal relationshiops between exposures and outcomes

Question 5

Which of the following sources could be used to
determine life expectancy:

Answer 5

National Vital statistics system

Question 6

Death certificate data in the United States include
which of the following

Answer 6

• Demographic Characteristics
• cause of death
• immediate cause
• contributing factor

Question 7

What is a hypothesis deefines as in the epidemoilogical research cycle?

Answer 7

Statement of research questuion in a way that allows for it to be tested.

Question 8

What is operationalization defined as in the epidemiogical research cycle?

Answer 8

Process of defining measurement
procedures for the variables used in
the study.

e.g: For example, in a study of the association between tobacco
use and lung disease, the variables might be designated as
number of cigarettes smoked and occurrence of asthma.
* The operationalization of these two variables might require a questionnaire to measure the amount of smoking and a review of the medical records to search for diagnoses of
asthma.

Question 9

What is the significance of clinical significance versus statistical significance?

Answer 9

• Clinical Significance: Reflects whether a finding is meaningful for patient outcomes
• Statistical Significance: Indicates whether an observed effect is likely due to chance
• *relies on use of p-values which are the probability that we would observe the association we did in our sample if the null hypothesis is true

Clinical significance focuses on real-world impact, while statistical significance relies on p-values.

Question 10

What are the two types of associations in epidemiology?

Answer 10

• No association: X not related to Y (e.g: taking an epidemiology course is unrelated to learning business)
• 4 types of association*Non-Causal: X does not cause Y ((Dietary sugar intake and occurrence of diabetes) could be randome associationCausal: X causes Y (Smoking cigarettes causes lung cancer)
  Direct causal : Consumption of large amounts of sugar is directly related to the occurrence of diabetes without involvement of an intermediate step.
  .

    **Indirect causal**: 
              excessive sugar consumption might be related to obesity, which in turn is related to diabetes. Thus obesity is an intermediate step between sugar consumption and diabetes.

Question 11

What are case-control studies

Answer 11

*Subjects are first defined on the
basis of presence or absence of
outcome of interest.
▪ Cases are those individuals who
have outcome or disease of interest,
whereas controls do not.

Question 12

What are retrospective cohort studies?

Answer 12

*cohort studies trakc incidence rate of a disease over a period of time
*Uses historical data to determine exposure level at
some baseline in the past
*Follow-up for subsequent occurrences of disease
between baseline(initiation) and present is performed often
using historical (or existing) data.
Mixed Cohort Combines retrospective and prospective
approaches

Question 13

What are prospective cohort studies

Answer 13

Subjects are classified according to their exposure
to a factor of interest and then are observed over
time to document the occurrence of new cases
(incidence) of disease or other health event

e,g: healthy peeople who had an exposure –> time passes so now healthy people and sick people are document to determine the occurence of new disease

Question 14

What is relative risk

Answer 14

** the measure of association used in cohort studies
** incidence rate of a disease/health outcome in exposed group/ incidence rate in non exposed group

• A/A+B / C+C/D

Question 15

What is an odds ratio? How do you interpret it?

Answer 15

A measure of association between exposure and an outcome, calculated in case-control studies
*AD/BC
* If OR> 1 there is positive association between exposure and disease.
* if OR<1 exposure might be a protective factor
* if OR=1.0 no association between exposure and outcome.

mutliply diagonaly

It helps determine the strength of the association.

Question 16

What are clinical trials and what are the phases

Answer 16

A research activity that involves the administration of a
test regimen to humans to evaluate its efficacy and
safety

1. phase I: safety and dosing
2. phase ii: efficacy and dose optimization
3. phase iii: eficacy and safety

Question 17

What are quasi-experimental designs and what are their purpose?

Answer 17

• research in
  which the
  investigator
  manipulates the
  study factor but does
  not assign individual
  subjects randomly to
  exposed and
  nonexposed groups
  e.g: two populations both w tooth decay but one is given fluoride one is not
• purpose: To evaluate interventions when random assignment is not feasible

They provide valuable insights despite potential biases.

Question 18

Determine whether all discussed studies are analytical or Descriptive

Answer 18

*Case report/series: descriptive
* Ecologic:either
* cross-sectional: either
* case-control: analytic
* prospective cohort: analystic:
* retrospective cohort: analystic:
* mixed cohor :analytic
* experiemntal: analytic

Question 19

What are randomized controlled trials used for?

Answer 19

subjects are randomly put into control or test groups

To determine the efficacy of interventions by randomly assigning participants to groups

These trials are considered the gold standard in clinical research.

Question 20

What are the three factors affecting the valitdy of the study?

Answer 20

1. External validty: ability to generalize from the result of the study to a wider external popualtion
2. internal validy: degree to which a study is conducted using methodologiclaly sound procedures
3. Bias: results from inferences form a study are systematically different from the truth in a way that is not random

Question 21

What are the four types of bias define them

Answer 21

selection bias: results form how indivisuals are selected for the study
*e.g: the healthy worker effect
information bias; results from how measurements of exporsure or heath outcomes were taken
* e.g: recall bias and family recall bias (when cases
are more likely to remember the details of their family history than are controls )

Hawthorne effect: Results from participants’ behavioral
changes as a result of their knowledge of
being in a study

Confounding: The distortion of a measure of the effect of
an exposure on an outcome due to the
association of the exposure with other
factors that influence the occurrence of the
outcome

Question 22

What are experimental studies

Answer 22

they are interention studies where an investiagion involving an intentional change in some aspect of the status of the subjects

*Randomized controlled trials (RCT )
*Quasi-experiements

Question 23

Define big data in epidemiology

Answer 23

Massive and continuously generated digital datasets characterized by:
* Volume: Enormous amount of data requiring flexible storage
* Variety: Different formats (text, images, videos)
* Velocity: Generated in near real-time

Big data plays a crucial role in analyzing and understanding epidemiological trends.

Question 24

What are the applications of big data in epidemiology?

Answer 24

• Data Linkage: Joining data elements across databases using common identifiers
• Data Mining: Analyzing large datasets to identify patterns and associations

These applications help in enhancing public health responses and research capabilities.

Question 25

List the four key factors that determine epidemiologic data quality

Answer 25

* Nature of the data * Data availability:Accessibility and HIPAA compliance (removing personal identifiers) * Population coverage:How well the data represents the population of interest * Appropriate use:Suitability for specific research questions ## Footnote Understanding these factors is essential for accurate epidemiological analysis.

Question 26

What are the four online retrieval sources?

Answer 26

* Public websites (CDC, NIH, WHO) * Medical databases (MEDLINE) * Professional organizations (American Public Health Association) * Academic journals (American Journal of Epidemiology)

Question 27

What entails a case report? provide examples

Answer 27

*Accounts of a single occurence or small colleciton of noteworthy health-related incidents *Often document unusual presentations, treatments, or disease manifestations e.g:CDC reports on rare diseases, unusual outbreaks

Question 28

What are ecologic studies? what is the ecologic fallacy?

Answer 28

…a study in which the units of analysis are populations or groups of people rather than individuals The ecologic fallacy is an erroneous inference that may occur because an association observed between variables on an aggregate level does not necessarily represent or reflect the association that exists at an individual level;…” Read the examples in your book ☺

Question 29

What is public health surveillance? Give examples

Answer 29

* Systematic and continuous collection of disease and health data * Nationally Notifiable Diseases (COVID-19, HIV, tuberculosis) ## Footnote It monitors communicable diseases, non-infectious conditions, and risk factors.

Question 30

What is the role of vital registration systems in epidemiology?

Answer 30

Maintained by individual states, territories, and jurisdictions, it collects data through certificates for: * Deaths * Births * Marriages * Divorces * Fetal deaths ## Footnote Vital registration systems provide critical demographic data for health analysis.

Question 31

Death certificate data in the united states include?

Answer 31

* demographic characteristics * cause of death * immediate cause of death * contributing factors

Question 32

What are case registries in epidemiology?

Answer 32

Centralized databases for specific diseases, such as: * Cancer registries * National Program of Cancer Registries (NPCR) * Surveillance, Epidemiology, and End Results (SEER) ## Footnote These registries track incidence, survival rates, and treatment outcomes.

Question 33

What are the criteria of causality of Braford Hill and their definitions?

Answer 33

* Strength of Association * Consistency * Specificity * Temporality * Biological Gradient * Plausibility * Coherence * Experiment * Analogy ## Footnote These criteria help evaluate whether an association is likely causal.

Question 34

Biologic Gradient

Answer 34

* Also known as a dose- response visualized by a dose-response curve * Shows a linear trend in the association between exposure and disease

Question 35

What entails a case series? Give an Example

Answer 35

*Collection of multiple similar cases grouped together with common features ** Typically includes patient characteristics, symptoms, treatments, and outcomes ** Often used when little is known about a condition or to document unusual patterns e.g: **Medical journal reports documenting features of multiple patients with the same condition

Question 36

Analogy

Answer 36

Relates to the correspondence between known associations and one that is being evaluated for causality

Question 37

what is braford Hills definition of experiement

Answer 37

Evidence from experiments (e.g., public health interventions) can help support the existence of a causal relationship. he cause must be observed before the effect

Question 38

What are the types of descriptive epidemiologic studies?

Answer 38

* Case Reports * Case Series * Cross-Sectional Studies ## Footnote Each type serves different purposes in documenting health-related incidents.

Question 39

Define braford hill's strength of association

Answer 39

strong associations give support to a causal relationship between factor and disease

Question 40

What differentiates vital statistics from reportable disease statistics?

Answer 40

Vital Statistics: data from recording burths and deaths * Source: Vital registration system * Content: Demographic data, causes of death * Coverage: Comprehensive Reportable Disease Statistics: statistics derived from disease that physicians must report to gov agencies ususally communicable diseases. * Source: Disease surveillance systems * Content: Case counts, demographics * Purpose: Early detection of health threats *Examples:CDC's National Notifiable Diseases Surveillance System

Question 41

What are the applications of Public Health Surveillance Programs

Answer 41

: Monitor communicable diseases, non-infectious conditions, and risk factors

Question 42

What is descriptive epidemiology?

Answer 42

A branch of epidemiology that focuses on: * Evaluating trends in health and disease * Monitoring known diseases * Identifying emerging health problems ## Footnote It supports health planning and guides efficient resource allocation.

Question 43

What is the struture of public health surveillance programs?

Answer 43

Multi-level system (local, state, federal) with standardized reporting

Question 44

Distinguish between deterministic and probabilistic causality and sufficient compoenent cause.

Answer 44

* Deterministic Causality: Claims a cause is invariably followed by an effect * Probabilistic Causality: Describes the probability of an effect given a particular dose *sufficient component causality: together a group of component cause smake up a suffiencient cause complext ( e.g: poor exercise, poor nutrition lack of sleep all contribute to obesity)

Question 45

What are the uses of descriptive epidemiology?

Answer 45

*Evaluate trends in health and disease *Support health planning and evaluation *Generate hypotheses for further investigation

Question 46

Define temporality

Answer 46

the cauase must be observed before the effect

Question 47

Define what necessary/ sufficient means and Describe each of the 4 types of deterministic models of causality

Answer 47

Necessary :[a] factor whose presence is required for the occurrence of the effect.” Sufficient: " cause that is sufficient by itself to pro- duce the effect." X is cause/exposure and Y is health outcome ** Necessary and Sufficient: ** *“Both X and Y are always present together, and **only** X is needed to cause Y…” * Huntington’s disease is caused by a specific genetic mutation. If the mutation is present, the person will develop the disease, and without the mutation, the disease will not occur. **Necessary but not Sufficient** * X is one of the causes of the disease, but there are other causes. * ghe bacteria Mycobacterium tuberculosis is necessary to cause TB, but not sufficient on its own. Factors like a weakened immune system or poor living conditions are often needed for the disease to manifest. **Sufficient but not Necessary** High radiation exposure can cause cancer, but cancer can also occur from smoking, genetic predisposition, or other carcinogens. Radiation exposure is sufficient to cause cancer but not necessary. **Neither necessary nor Sufficient ** *X may or may not be present when Y is present. Under these conditions, however, if X is present with Y, some additional factor must be pres- ent. Here X is a contributory cause of Y *e.g:(e.g., coronary heart disease has many contributing causes non of which are sole contributors) * Poor diet, lack of exercise, smoking, and genetic factors all contribute to heart disease. None of these factors alone are necessary or sufficient, but together they increase the risk.

Question 48

consistency

Answer 48

An association has been observed repeatedly

Question 49

What variables are considered in descriptive epidemiology?

Answer 49

* Person Variables * Age *Sex/gender (biological differences) *Race/ethnicity *Socioeconomic status * Place *International comparisons (Differences in disease patterns across countries) *National Patterns *urban-rural differences *localized patterns * Time * Secular trends( long term changes in disease freq) *cyclic or seasonal trends( regular patterns occuring within a year or across multiple years) * point epidemics( sidden outbreaks with a sharp increase and dexrease in cases) * clustering ( closely grouped cases with defined distribution paterns in time,place or both) ## Footnote These variables help understand the relationships between health outcomes and exposures.

Question 50

define plausibility

Answer 50

The association must be biologically plausible from the standpoint of contemporary biologic knowledge

Question 51

define specficity

Answer 51

Association is constrained to a particular disease– exposure relationship

Question 52

What entails a cross-sectional study? give an example

Answer 52

* prevalance study that examines relationships between health outcomes and exposures at a single point in time ** "Snapshot" approach capturing prevalence rather than incidence e.g:The Behavioral Risk Factor Surveillance System (BRFSS) con- ducts an ongoing survey (using random digit dialing tech- niques) of civilian, noninstitutionalized U.S. residents age 18 years and older. This section presents sleep data gathered by BRFSS during 2014.

Question 53

What is the epidemilogic inference process in 4 steps

Answer 53

1. Make observations about disease patterns 2. Generate comparisons between populations or subgroups 3. Formulate hypotheses based on observed differences 4. Test these hypotheses with more rigorous analytical studies

Question 54

coherence

Answer 54

…the cause-and-effect interpretation of our data should not seriously conflict with the generally known facts of the natural history and biology of the disease…