Study types Flashcards
What does every single study have?
All components of PECOT
List the 5 components of PECOT
Participants Exposure group Comparison group Outcome Time
What are the two methods of data collection?
Numerical and categorical
What is an example of a numerical data collection?
Weight in kg
What is an example of a categorical data collection?
Not in numbers and is grouped into a category
E.g Underweight, normal weight, overweight
What are the measures of occurrence?
Incidence and prevalence
Define incidence
Calculating the onset of disease for OVER a period of time
Define prevalence
Calculating the number of people with a disease at ONE point in time
Which is the better measure of occurrence and why
Incidence
Keeps the denominator (i.e gives an idea of the proportion of people affected)
Not affected by the death and cure rate
When is an incidence measure used?
Used for dis-eases which have an easily observable onset
It is easy to tell when people transition from non dis-eased to dis-eased
What are the two sub-types of a prevalence measure?
Point prevalence and period prevalence
What is point prevalence?
Used for dis-eases when the onset is not as easy to observe
What is period prevalence?
Dis-ease outcome is measured at one point in time BUT have occurred over a previous period of time
Used for dis-eases where the onset may be easy to observe but may come and go/vary in severity
E.g Asthma
What are the 4 different study types?
Cohort study
Cross-sectional study
Randomised Control Trial
Ecological study
What is a cohort study used for?
To investigate associations between risk factors (exposures) & dis- ease incidence in different groups of individuals
What is an application of a cohort study?
When investigating the causes of dis-ease incidence.
What are the design features of a cohort study?
Longitudinal, observational (non-experimental) Participants allocated to exposure & comparison by measurement
Dis-ease outcomes measured during follow-up
What are strengths of a cohort study?
Usually cheaper than RCTs.
Exposure usually measured before outcome, avoiding recall bias and providing clear time sequence between exposure and dis- ease outcomes.
What are some weaknesses of a cohort study?
Confounding is common.
Maintenance error very common in long term studies because exposure is not controlled by the investigators.
Is a cohort study a prevalence or incidence measure?
An incidence measure
People tend to be followed over time (observational)
What is a cross-sectional study used for?
To measure dis-ease prevalence in defined groups / populations of individuals. To investigate associations between risk factors & dis-ease prevalence in the group
What is an application of a cross-sectional study?
Measuring the prevalence of dis-ease in different groups & populations
What are some design features of a cross-sectional study?
Cross-sectional, observational, (non- experimental). Participants allocated to exp & comp by measurement Dis-ease outcomes measured at same time of allocation
What are the strengths of a cross-sectional study?
Generally cheaper & can be completed more quickly than RCTs or cohort studies.
Best design for assessing the prevalence of dis-ease in a population.
No maintenance error as no follow-up
