Critical numbers Flashcards
(28 cards)
Define standard deviation
a measure of the average distance of the data observations from the mean value
Define odds ratio
a ratio of odds in 2 groups, often used in case control studies as an approximation to estimating relative risk
Median
the middle observation when data is arranged in order of increasing values. Often used to describe skewed or ordinate data
Where is the true value likely to be?
Within the confidence interval
IQR
represents the observation below which the bottom 25% of data lie and above which the top 25% of data lie
p value
Represents the probability of observing a test statistic at least as extreme as that actually observed if the null hypothesis is true. A small p value is interpreted as strong evidence against the null hypothesis
Mode
Most common value - used to describe nominal or ordinal data
Standard error
For estimation - describes the precision of the mean. Tell us how far from the true value (population mean) the sample mean is
Primary prevention
Prevention of disease from occurring in people who have not been diagnosed as having the disease by reducing risk factors. Includes health promotion e.g. smoking cessation reduces risk of CVD
High risk approach to prevention
Targeting of health promotion to groups based on information from epidemiological studies e.g. Clamydia screening for people age 15-24
Population approach
Aims to lower the level of of risk in a population, includes health promotion
Prevention paradox
A prevention measure which brings much befit to the population, but may offer little to each participating individual
Absolute risk
Probability / risk of an event or developing disease within a stated time period
Relative risk
Probability / risk of an event or developing of a disease relative to exposure
Tertiary prevention
Preventing progression of an established disease. Aims to reduce the impact of a disease (limiting disability caused by disease or preventing recurrence of events) and promotes quality of life through active rehabilitation e.g. prescribing aspirin to patients post-MI
Ecological study
Observational / descriptive, uses routine data from populations, looks at prevalence, trends and correlations e.g. census or death certificates
Cross-sectional
Observational / analytical; uses information from individuals to update or supply prevalence data (ONLY) Gives you a snapshot at that particular point in time
Analytical
Observational (vs intervention); analytical of relationships rather than simply descriptive
Cohort study
PROSPECTIVE
Observe a large number of people without a disease over a long period then compare incidence between groups that differ in terms of exposure
EXAMPLE: determine who smokes in the particular population and observe how many of the smoking cohort go on to develop lung cancer and how many non-smokers do
Longitudinal
Observational study of persons over a period of time taking measurements at more than one time point
Association
Existence of a relationship between variables
Case-control
RETROSPECTIVE Observational study identifying persons with the disease of interest and comparing them with a suitable control group (without disease)
EXAMPLE: comparing a group of people with lung cancer to those without lung cancer and seeing how many of the people in each group smoked
Retrospective
Analysis of events that occurred before the onset of disease
Epidemiology
the study of frequency, distribution and determinants of disease within a population, in order to prevent / control disease
