Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Research & Stats > Week 10 - Observational Studies (FLIPPED CLASSROOM) > Flashcards

Week 10 - Observational Studies (FLIPPED CLASSROOM) Flashcards

1
Q

STUDY DESIGN SUMMARY

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

What are the characteristics of Cross-sectional studies?

A

-Random sample recruited from source population
-At specific time point
-Exposure and outcome assessed simultaneously

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

What are the two types of cross-sectional studies?

A

1.Descriptive = assessment of only one variable at a time
2. Analytic = assessment of associations between 2 variables

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

At what time is exposure and outcome assessed?

A
  • At a specific time point
    -THUS simultaneously
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do you call cross-sectional studies done annually or biannually by countries?

A

-Surveys

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

What are the 3 descriptive measures of observational studies?

A

-Proportions (categorical variables)
-Prevalence (binary categorical variables)
-Mean/Median (numeric variables)

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

What are three measures of association in cross-sectional studies?

A

-Odds ratio (binary categorical outcomes)
-Mean diff (categorical exposure vs numeric outcome)
-Regression/ correlation coefficient (numeric exposure vs numeric outcome)

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

What are the advantages of cross-sectional studies?

A
  1. Easy to perform
  2. Less costly
  3. Opportunity to readily assess prevalence of disease in population THUS results are of high relevance to public
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the disadvantages of cross-sectional studies?

A
  • Observational study THUS self-reports THUS information bias
    -Observational study THUS prone to confounding
  • Impossible to assess risk (incidence)
    -Impossible to assess temporality in association (BECAUSE TESTED SIMULTANEOUSLY)
    -Not appropriate for inferring causality (HIGH LIKELIHOOD OF REVERSE CAUSATION)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

CASE CONTROL STUDIES SCHEMATIC DIAGRAMs

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

What are the characteristics of case-control studies?

A
  1. A group of patients with specific disease is recruited (CASE GROUP)
  2. Recruit a random sample of individuals NOT suffering from specific disease (CONTROL GROUP)
  3. Control group must be recruited from same source population as case group
  4. Control group can be recruited from general population (preferred) OR hospital patients not suffering from this specific disease
  5. Case and control group is usually matched for key characteristics (age, gender, etc) = ELIMINATES CONFOUNDING
  6. Matching restricted factors should be limited to 2-3. Overmatching = avoided. INSTEAD other confounders should be adjusted in analysis
  7. Assessment of a series of exposures in cases and controls that occurred in the past
    RETROSPECTIVE (start with disease and look back in time for identification of exposures)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the measures of association of case-control studies?

A

-Odds ratio (categorical exposures)
-Mean diff (numeric exposures)
ALWAYS BINARY OUTCOMES FOR CASE CONTROL STUDIES

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

What are the descriptive measures for case-control studies?

A

NEVER CALCULATED FOR CONTROL_CASE
ONLY ANALYTIC!

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

What are the advantages of case-control studies?

A

-Possible to investigate rare diseases
-Easy to perform (not as much as cross-sectional studies)
-Cheap (not as much as cross-sectional studies)
- Possible to assess several exposures and potential confounders for a single outcome
-Possible to investigate early exposures in life in relation to disease outcomes later in life.

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

What are the disadvantages of case-control studies?

A

-It’s an observational study THUS information bias (measurements based off self-reports)
-Prone to recall bias (based on self-reports of events from years back)
-Observational study THUS confounding
-If control group is not a representative sample of source population = selection bias
-Impossible to assess risk (incidence) of disease
-Difficult to prove causality due to bias and confounding

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

COHORT STUDIES DIAGRAM

A
17
Q

WHAT ARE THE CHARACTERISTICS OF COHORT STUDIES?

A

-Random sample selected from source population
-All participants suffering from the disease are EXCLUDED
-At study initiation (study baseline) all exposures of interest are assessed.
-Participants continue their lives normally and researchers record new cases during FOLLOW-UP
-Disease confirmation may occur from clinical examination (preferred), hospital or national registries or self reports in specific time intervals
-During follow-up = reassessment of exposures to assess whether exposure to certain factors has changed over time
-Main aim of cohort studies = investigates whether incidence (risk) of different diseases differs based on different exposures
- Prospective

18
Q

What is the aim of cohort studies?

A

The main aim of cohort studies is to investigate whether
the incidence (risk) of different diseases differs based
on different exposures (exposed vs unexposed).

19
Q

What are the descriptive measures for Cohort studies?

A
  1. Incidence (binary variables)
  2. Mean/ median (numeric variables)
    VERY RARILY CALCULATED FOR COHORT STUDIES
20
Q

What are the measures of association for cohort studies?

A
  1. Risk Ratio (binary categorical outcomes)
  2. Rate Ratio (binary categorical outcomes, used when person-years can be calculated)
  3. Mean difference (categorical exposure vs. numeric outcome)
    ODDS RATIOS COULD BE CALCULATED WHEN BINARY OUTCOME IS VERY RARE
21
Q

What are the advantages of Cohort studies?

A
  1. Possible to assess risk (incidence) of disease and mortality THUS calculate relative risk
  2. Possible to assess temporal associations (prove that exposure precedes outcome)
  3. Possible to assess several exposures and outcomes THUS more informative and valid results
  4. Possible to investigate risk factors for chronic diseases (takes years to develop)
  5. Study samples usually large (Increases internal validty) (low random error)
22
Q

What are the disadvantages of Cohort studies?

A
  1. Information bias (self-reports) (Due to observational design)
  2. Selection bias due to selective drop
  3. Confounding (observational design)
  4. Difficult to assess risk of rare diseases (very large samples required)
  5. Huge costs and long duration
  6. Difficult to prove causality (but still easier than other observational studies)

Research & Stats (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions