Lecture 4- analytical studies Flashcards
what are analytical studies
are analytical studies based on population data
what 2 types Can analytical studies be
what are observational studies and what are the 2 categories involved
what is a case control study
What is it important to define in case control
what is a distinctive feature
what does a case control study look like
what are the advantages of case control studies
what are the disadvantages of case control studies
what is bias and what are the different types
what is selection bias
What is matching controls and cases referred to as
matching strata
what are the 3 purposes of matching strata
what is information bias
what is regression dilution bias (statistical)
what is the cohort study
what is the period of time for a cohort study
what does a cohort study look like
what does the study look like for low fibre effect risk for IBD
what are the advantages of a cohort study
what are the disadvantages of a cohort study
what does the study about high fibre diets reducing colon cancer look like and hat are its strengths and weaknesses
what is a randomised control trial
what do RCT ensure
what could the exposure variable be in an RCT
what 2 trails can an RCT be
what are the pros of RCT
what are the cons of RCT
what does the ability to prove causation vary with
what does the ability to study rare diseases vary with
what are the four types of ratio
OR- odds ratio
HR- hazards ratio
IRR- incident rate ratio
RR- relative risk ratio
what is OR
measures the strength of association between two variables. It is commonly used in case-control studies where the odds of exposure among cases (those with the outcome) are compared to the odds of exposure among controls (those without the outcome).
what is HR
measure of how often an event happens in one group compared to how often it happens in another group, over time. It is frequently used in survival analysis, particularly in studies where the time to an event (such as death) is of interest
what is IRR
measure of the rate at which new events occur in a population. It is often used in cohort studies where the incidence rates of an outcome in exposed and unexposed groups are compared
what is the RR
ratio of the risk of an outcome in one group to the risk of the outcome in another group. It is commonly used in cohort studies to measure the association between exposure and outcome
what does it mean if OR/HR/IRR/RR = 1
no effect of the exposure (such as fibre) on the risk of the disease (eg colorectal cancer)
what does it mean if the ratios are greater than 1
increasing risk
what does it mean if the ratios are less than 1
decreasing risk
what does it mean if the confidence interveral (CI) covers 1
the OR/HR/IRR/RR has no effect.
e.g OR 0.45 (0.32-0.84) exposure is decreasing risk and CI does not inlude 1.
ie OR 0.45 (0.32-1.84) exposure is not decreasing risk as the CI inludes 1.
What is the double blind RCT known as
The gold standard- shows cause and effect
what epidemiology only show
correlation
what is the case
someone with a disease- we always need to know what the disease is
what are controls
are healthy but have similar characteristics e.g age and sex match
what does a quintile mean
cutting a group into 5 things
what do we look into for the true value
relative risk, odds ratio, hazards ratio
what is recall bias
peoples past lifestyle
what is info bias
interviewee inaccurately remembers things
what is interviewer bias
interviwers asks questions differently to the 2 populations
what are the strongest studies
cohort studies - stronger than case control studies
