Modules 10-23 Onward Flashcards
What are different kinds of experimental studies?
clinical trials
prevention trials
therapeutic trials
community trials
What is a clinical trial?
are research studies that test a medical, surgical, or behavioral intervention in people. These trials are the primary way that researchers determine if a new form of treatment or prevention, such as a new drug, diet, or medical device (for example, a pacemaker), is safe and effective in people.
What is a prevention trial?
evaluates whether an intervention reduces the risk of a disease in a population that is / was free of said disease
What is a therapeutic trial?
Assesses new screening or diagnostic methods
What are community trials?
interventions aimed at the population level
considered quasi experiments
What is a randomized control trial?
The randomised control trial (RCT) is a trial in which subjects are randomly assigned to one of two groups: one (the experimental group) receiving the intervention that is being tested, and the other (the comparison group or control) receiving an alternative (conventional) treatment (fig 1).
What is the Hawthorne effect?
The Hawthorne effect refers to people’s tendency to behave differently when they become aware that they are being observed
What is the placebo effect?
The placebo effect is when a person’s physical or mental health appears to improve after taking a placebo or ‘dummy’ treatment.
What is the principle of equipoise
The principle of equipoise states that, when there is uncertainty or conflicting expert opinion about the relative merits of diagnostic, prevention, or treatment options, allocating interventions to individuals in a manner that allows the generation of new knowledge (eg, randomization) is ethically permissible.
What are the two measures of efficacy?
Superiority test (is one method better than the other?) and equivalence test (is one treatment no better or worse than the other?)
What is efficacy versus effectiveness?
Efficacy is the degree to which a vaccine prevents disease, and possibly also transmission, under ideal and controlled circumstances – comparing a vaccinated group with a placebo group.
Effectiveness meanwhile refers to how well it performs in the real world
Describe efficacy calculations
What is the measure of association for experimental epidemiology?
efficacy
what is blinding or masking?
Describe different methods of randomization
Describe the 4 phases of clinical trials
Describe different types of trial designs
Describe different types of controls and interventions
describe 3 types of trial outcomes
What is bias?
Bias is any systematic error in an epidemiologic study that results in an incorrect estimate of the association between exposure and the health outcome. Bias occurs when an estimated association (risk ratio, rate ratio, odds ratio, difference in means, etc.) deviates from the true measure of association.
What is external validity?
External validity is the extent to which you can generalise the findings of a study to other situations, people, settings, and measures.
What is internal validity?
Internal validity is defined as the extent to which the observed results represent the truth in the population we are studying and, thus, are not due to methodological errors.
What is the difference between systematic and random error?
Random error causes one measurement to differ slightly from the next. It comes from unpredictable changes during an experiment. Systematic error always affects measurements the same amount or by the same proportion, provided that a reading is taken the same way each time.
What is selection bias?
Selection bias is a distortion in a measure of association (such as a risk ratio) due to a sample selection that does not accurately reflect the population
Exclusion
Sampling bias
Loss to follow up?
What is sampling bias?
Error that occurs due to using a nonrandom sample
What is information bias?
A flaw in measuring exposure or outcome data that results in different quality or accuracy of information between comparison groups
e.g. misclassification bias, recall bias, reporting bias, interviewer bias, observer bias, measurement bias
Describe the effects of bias regarding the null hypothesis / association
Describe different types of errors
What is the difference between bias and confounding variables
with bias, associations are invalid and purely error
with confounding, associations are real but not causal
what is a confounding variable?
a variable which interferes with the search for causal association between exposure and outcome; masks relationship
Is related both to exposure and outcome