STUDY DESIGN - created from Mind Map

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ANALYTIC

DESCRIPTIVE

Observational

Experimental

Cohort

Case-control

Cross-sectional

best oservational study

mostly prospective

compare incidence of disease between exposed and non-exposed groups

Strength

Weakness

Example

Formula

study the effect of exposure

subject choose prior to disease recognition

difficult to follow up

unsuitable for rare disease

costly and need more time

Framingham Heart study 1948

Nurses' Health study 1976

Relative risk

Odds ratio

retrospective

compare past exposure between disease& non-disease

Strength

best for rare disease

Weakness

Example

Formula

less time & money required

inaccurate result due to confounded by other factors

prone to selection bias

Thalidomide 1962

Odds ratio

Present

best for measure prevalance

study exposure and outcome at a same time

Strength

Weakness

Example

can create hypothesis

less time & money

direct & simple

test many variables

Can't measure incidence

Can't determine cause effect

Not for rare disease

British Social Attitude survey 1983

Randomised control trial (RCT)

non randomised control trial

best experimental design

highest strength of evidence

Gold standard

Strength

randomly assign to intervention & comparison groups

Weakness

Example

prospective

determine cause effect

less bias

costly

unethical to certain intervention

long time follow up

MRFIT 1976

Standford community trials 1972-1992

Quasi experiment

same with RCT but without randomisation

Case report

Case series

Descriptive epidemiology

Detail study of single case

Strength

Weakness

Example

retrospective

provide depth understanding

detect adverse & beneficial effect of new drugs

not based on systemic study

the causes may have other explanation

Anna O 1895

Strength

Weakness

Example

retrospective

study of a case with similar diagnosed from single/multiple sources which report a unique condition

useful for rare disease with little exposure available

use to create hypothesis

can't study cause effect

Zika virus & Guillain-Barre syndrome-case series from seven countries 2015

study od disease determinant in term of time, place and person

Example

Present

strength

weakness

John Snow- Cholera outbreak in London 1854

provide information on disease & condition

determine population at greatest risk

assist in allocation of resources

bias in term of selection, information & confouding