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Flashcards in Part 2: Types of Studies Deck (42):
1

What are the 4 different studies?

1. RCT
2. Cohort
3. Cross-sectional
4. Ecological

2

What is a longitudinal study?

A study which goes through a period of time (over a long period of time)

3

What is the opposite of longitudinal study?

Cross sectional study (one point in time)

4

Which occurrence type can longitudinal studies be associated with?

Incidence

5

Which occurrence type can cross sectional be associated with?

Prevalence

6

Which studies out of the 4 are longitudinal?

RCT
Cohort
Could be Ecological

7

Which studies out of the 4 are cross sectional?

Cross-sectional
Could be Ecological

8

What is the usual study objective of RCT?

Investigate the effects of different interventions (exposures) on dis-ease incidence in different group of individuals

9

What is the usual study objective of Cohort studies?

Investigate associations (effects) between risk factors (exposures) and dis-ease incidence in different groups of individuals.

10

What is the usual study objective of Cross-sectional studies?

To measure dis-ease prevalence in defined groups of individuals.

Investigate associations between exposures and dis-ease prevalence in the groups.

11

What is the usual study objective of Ecological study?

Investigate associations between exposures and dis-ease prevalence or incidence in different groups of populations.

12

Which studies have individuals?

RCT
Cohort
Cross-sectional

13

Which study sees groups of populations rather than individuals?

Ecological

14

What is the most useful application of the RCT?

Effect of interventions like in:
- New therapies
- Drugss

15

What is the most useful application of the Cohort?

Studying the causes of dis-ease incidence or the effects of interventions

16

What is the most useful application of the Cross-sectional?

Measuring the prevalence/burden of dis-ease in different groups and populations

17

What is the most useful application of the Ecological?

Studying trends and causes of dis-ease incidence and prevalence

18

Which studies are experimental?

RCT
Could be Ecological

19

What is the opposite of experimental?

Observational

20

Which studies are observational?

Cohort
Cross-sectional
Could be Ecological

21

What does observational mean?

That the study undertakers are only viewing the participants, not forcing them to use anything (ethical)

22

What does experimental mean?

We do not know the outcome (like a new drug) so it could be bad or good but we are essentially experimenting on people in the RCT trials

23

How is RCT allocated?

Random

24

How is Cohort study allocated?

Measurement

25

How is Cross sectional allocated?

Measurement (usually by questionnaire or survey)

26

How is Ecological allocated?

Could be random or measurement

27

What does random allocation give rise to?

No confounding, allocation non random error

28

What does measurement error give rise to?

Confounding (allocation non random error)

29

Which studies have confounding?

Cohort
Cross-sectional
Ecological

30

What is the weakness of longitudinal studies?

Long time give rise to
- maintenance error
- also $$$$$$$$$$$

31

What gives rise to cross sectional (quick) studies?

Quick,
- no maintenance issue
- cheap as $

32

What is the main strength of RCT? (1)

Limited confounding

33

What is the main strength of Cohort studies? (2)

Usually cheaper than RCT (even though longitudinal)

E measured before O so NO recall bias

34

What is the main strength of Cross-sectional studies? (3)

Cheap

Quick, no follow up so NO MAINTENENCE

Best design for assessing prevalence/burden of dis-ease in population

35

What is the main strength of Ecological? (3)

Cheap

Quick

Efficient for rare outcomes

36

If a study is generally quick (no follow up) what does this have a positive for?

No maintenance non random error

37

What are the main weaknesses of RCT?

Ethical limitations

$$$$$$$$ so normally small participants so more random error and could be statistically insignificant

Maintenance error common

38

Which studies have follow ups?

RCT
Cohort
Could be ecological if it is a collection of RCT's

39

What can follow up's lead to (the weakness)

Maintenance non random error

40

What are the main weaknesses of Cohort?

Confounding (due to measurement allocation)

Maintenance error (long term studies because exposure is not controlled by the invesitgators)

41

What is the main weakness of Cross-sectional studies?

Uncertain time sequence so reverse causality

If period prevalence, can be subject to recall bias

Confounding (allocation is by measurement; survey)

42

What is the main weakness of Ecological studies?

Confounding very common