Quantitative Approach - Groups - Observational Flashcards
What is the quantitative observational approach?
Observe the explanatory factor
Divide into groups based on explanatory factor
Compare outcome measure between groups
What is the quantitative groups approach?
Create groups of participants that differ in terms of the explanatory factor
Measures outcome measure in these groups
May tell us about a relationship between the explanatory factor and an outcome of interest
What are the advantages of the quantitative observational approach?
May be more ethical:
Cannot deliberately expose someone to a hypothesised risk factor for a disease
Allows study of phenomena in their natural setting: more applicable to real world: “external validity”
Easier and cheaper to set up
Allows research on topics not amenable to experimentation - Sometimes it is not possible to manipulate the explanatory factor: gender
What are the disadvantages of the quantitative observational approach?
Possibility for bias - harder to control
Not all starting off at same point
Susceptible to confounding factors - but can be mitigated using statistics
Difficult to establish causal relationship between outcome measure and explanatory factor
What are confounding factors?
Occurs when you find a relationship between an explanatory factor and outcome measure but this is in fact as a result of an alternative factor
What is the quantitative observational cross sectional approach?
Measurement of EF and OM take place a same time
e.g. Do males consume more alcohol than females?
What is the quantitative observational longitudinal approach?
Measurement of EF takes place first and measurement of outcome measure takes place later (perhaps over several years, repeatedly)
Is fruit/ veg consumption in childhood related to blood pressure in adulthood?
What are the advantages of the quantitative observational cross sectional approach?
Quick
Easy and cheap
Suitable for research questions where the explanatory factor doesn’t change over time (e.g. sex, presence of a particular gene)
Ideal for determining the prevalence of a disorder (number of cases in a given population)
Not as much problem with attrition
What are the advantages of the quantitative observational longitudinal approach?
Can track changes over time
Can help establish cause and effect between EF and OM
May be less susceptible to confounding
What are the disadvantages of the quantitative observational longitudinal approach?
Expensive
Time consuming need to consider attrition
What is a quantitative observational longitudinal cohort study?
Identify groups based on EF
See whether outcomes are different to determine if EF affected outcomes
Can be prospective:
Recruit people without disease/ condition - measure EFs
Follow up some time later - determine who now has the condition
Can be retrospective:
Recruit representative sample some will have disease, some will not
Look back and see who had risk factors of interest in past (self report, medical notes)
What are the advantages of the quantitative observational longitudinal cohort study?
Much quicker and cheaper than prospective cohort study
Can be used to measure incidence
Retrospective cohort studies can be relatively quick
What are the disadvantages of the quantitative observational longitudinal cohort study?
Need a large sample, especially when studying rare diseases - therefore costly
Difficult to manage when there is a long latency between risk factor and outcome
Very lengthy if prospective
Difficulty assessing risk factor if retrospective
Need to consider attrition
What is the quantitative observational longitudinal case control study?
Recruit people with or without disease
Ask about exposure to past risk factors (or obtain from medical records)
Which factors predict outcomes?
What are the advantages of the quantitative observational longitudinal case control study?
Much cheaper and quicker than prospective cohort study
The only feasible way to study rare diseases
When disease incidence low need unfeasibly large numbers of participants in a cohort study to be reliable
