Week 4 Flashcards
What is epidemiology?
It is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to control the health problems
What is the difference between observational and interventional studies?
Observational study: the researcher does not alter what occurs and provides no intervention
Interventional study: the researcher intervenes to change the reality and then observes the outcome
What are the types of descriptive?
- Case study
- Case series
- Cross-sectional survey
What are the two types of observational analytical studies?
- Cohort studies
- Case-control studies
What are descriptive studies used for?
- Describe patterns of disease occurence in relation to person, place and time
- is used to generate a hypothesis
What is the difference between a cohort study and case-control study?
A cohort study is where in both exposed and not exposed groups see who develop disease and who do not (Exposure –> disease).
A case-control study look at who had the disease and then check for both groups who was exposed and who was not exposed (Disease –> exposure)
What is a control group in a study?
It is a comparison group which is as alike as possible to the study group except in the factor being studied.
What type of study is a randomised controlled trial (RCT)?
Its a prospective, interventional study
What is confounding?
This is where there is an apparent association between a presumed exposure and an outcome, is in fact accounted for by a thrid variable not in the postulated casual pathway. It is a variable that is independently associated with both presumed exposure and outcome
What are the ways to minimise confounding?
Restriction: restrciting who can participate in the study by only allowing specific people (e.g. age, gender, SES etc) to take part
Matching: by matching someone in the study group as closely as possible to a person in the control group (except for in the factor that is being studied)
Randominsation: allocating people to the study or control group purely by chance. This assumes that the confounding factors are equally spread among the two groups
What is the best method for minimising confounding?
Randomisation. This is as it equally distrubutes confounding factors across both arms of the study, confounding factors that we know about and those that we dont.
What are the three main types of bias?
- counfounding
- selection bias
- information bias
What is selection bias?
This refers to bias that occurs in the selection process. It distorts the ‘study factor-outcome’ relationship in the study for that present in the target population.
If you guys know a better way to word it go for it.
What is information bias?
This occurs when the information is collected differently between the two groups (control and study group)
What are the two types of information bias?
- Recall bias or rumination bias
- interviewer bias
What are the three types of blinding and explain them.
Un-blinded: both the study participants and the investigators are aware which groups have been allocated the control and the intervention
Single blinded: the study participants or the investigators do not know which arm of the study theey are involved in
Double blinded: both the study participants and the investigators do not know which participants recieved the intervention or the control
Here, have an inspirational quote…
“From learning the names of bones to fixing them, from every ‘ewww’ to every ‘woahhh,’ from every ‘its stinky’ to ‘im used to it,’ from buying your first lab coat to owning one with your name written on it. You are going to win. You are going to live your dream.”
What is random error?
This is where presummed association is due to chance. This can occur if the sample size is too small.
Define incidence?
This is the number of new cases arising in a given point of time
Define prevelance?
This is the number of exisitng cases with a health factor in a given period of time
What is the equation to calculate prevalence?
total number of cases/total population
What is the equation to calculate incidence?
number of new cases occuring over a period of time/number of people at risk
where number of people at risk is the risk of the event or the disease happening
If the incidence of disease is low, but the duration of the disease is long will the prevalence be high or low?
The prevalence will be high
If the incidence of a disease is high but the duration of the disease is short will the prevalence be high or low?
The prevalence will be low
What are the three factors that need to be considered when comparing incidence between populations?
- Make sure the same population unit/size is in the denominator
- Make sure the same period of time is compared
- The age distribution in the population
What is age-standardisation and why is it important?
- Age-standardisation takes into account the different age structures of a population (e.g. if one population has a shorter life span)
- This is done so you compare data between different populations
