Definitions Flashcards
Absolute Risk
The risk of having a disease calculated from the incidence
Alternative hypothesis
A question, framed in the positive, which seeks to test the relationship or difference between variables (see also Null hypothesis).
Bias
The process leading to the deviation of results from the true values.
Case-control Study
A retrospective study that begins by identifying a group of patients with a condition, matched to a group of similar patients without the disease, the exposure of different factors can then be compared between the two groups.
The rate of confounding bias is high in this type of study therefore it cannot be used to prove cause and effect but is often used as evidence to warrant undertaking a prospective study. Case-control studies are also particularly useful for rare conditions (where it would be difficult to recruit enough current patients) or those with a long latency period (where the follow-up period would be long).
Case Report
A description of a single unique patient.
Case Series
An accumulation of case reports pointing to a similar cause, often referred to as
anecdotal evidence, which is not reliable evidence but may justify undertaking a
controlled study.
Clinical Significance
A study is clinically significant if it has the potential to influence or bring about a change
to practice.
Cohort Study
A longitudinal study which follows two cohorts (groups) of patients, one which has been
exposed to the risk factor and one that hasn’t. The patients are followed for an extended
period and the disease development rate in each group compared.
Confidence Intervals/Limits
This quantifies the uncertainty in the results. The study is carried out on a sample from
an entire population and therefore the mean for the sample may not be the same as the
population mean. 95% confidence intervals provide the range of values within which we
can be 95% certain that the true population mean lies.
