what is a confidence interval?
tells us the range of values that a true population treatment effect is likely to lie
what are types of controlled studies?
- cohort
- case control
what type of study would apply to the following scenario: researchers watch what happens to a group of people, a group of patients has disease A and is treated with drug X
observational uncontrolled study
what type of study would be done when identifying new disease outcomes or a hypothesis generation?
case report/case series
what are the disadvantages of a case report/case series?
- cannot demonstrate valid statistical associations
- lack of control group
what is a case report/case series?
a report on a single patient of series of patients with an outcome of interest (no control group involved)
what is a cross-sectional study?
the observation of a defined population at a single point in time
- exposure and outcome are determined at the same time
if you were estimating prevalence of a disease or investigating potential risk factors, what type of study would you use?
cross-sectional study
what are the disadvantages of a cross-sectional study?
- causality (everything collected at once)
- confounding factors
- recall bias
what is a case-control study?
the study of people with a disease and a suitable control group of people without the disease
if you were looking at potential causes of disease, what type of study would be used?
case-control study
what are some disadvantages of case control studies?
- confounding factors
- recall/selection bias
- selection of controls
- time relationships
what is a cohort study?
- establish a group of individuals in population
- measure exposures
- follow up over period of time
- identify those that develop disease
if you were:
- estimating incidence of disease
- investigating causes of disease
- determining prognosis
- studying timing and direction of events
what type of study would you use?
cohort study
what are some disadvantages of cohort studies?
- controls difficult to identify
- confounding factors
- blinding difficult
- for rare diseases, large samples needed
- very time consuming/expensive
what are the best kind of studies to undertake?
randomised control studies
what are the four design elements of randomised control trials?
- specification of participants (inclusion/exclusion criteria)
- control/comparison groups
- randomisation
- blinding/masking
what is the function of blinding/masking in RCTs?
to prevent bias
what are some disadvantages of randomised control trials?
more difficult to design and conduct that observational studies
- ethical issues
- feasibility
- costs
