Definitions Flashcards
Define attributable risk
Measure of exposure effect that indicates how much greater frequency of disease is in the exposed group vs unexposed. Risk attributable to exposure of interest.
How is attributable risk calculated
Incidence in the exposed-incidence in the unexposed
Define incidence
No. of cases of the outcome of interest occurring in a defines population of a defined period of time. Probability or risk
How do you calculate odds ratio
odds of exposure in diseased group/ odds of exposure in the disease free group
Define odds ratio
Ratio between two odds that is reported in case-control studies instead of relative risk
How is odds ratio interpreted
1 = no association
>1 exposure more likely in case group
<1 exposure less likely in case group
Define prevalence
No. of cases of an outcome of interest in a defined population at a particular point in time
How is point prevalence calculated
No. of cases in a defined population at one point/ no. of persons in a defined population at one point
Define P value
The probability of obtaining the study result if the null hypothesis is true
What is the difference between prevalence and incidence
prevalence is all the cases at present while incidence is NEW cases
Describe relative risk
Measure of association between an exposure and disease as a ratio of incidence rate in the exposed group and the incidence rate in the non-exposed group
How is relative risk calculated
Incidence in the exposed group/incidence in the unexposed group
How is relative risk interpreted
1 = incidence in the exposed and unexposed are identical >1 = positive association
Define sample
A relatively small number of observations from which a population is described
Define variation
Variation of observations in a single sample
What do you take into account when evaluating statistical association
Chance
Bias
Confounding
Causal effect
Define routine data
data that are routinely collected and recorded in an ongoing systematic way, often for administrative or statutory purposes without a specific research question
Give examples of routine data
deaths, hospital admissions, screening, immunisation uptakes, census counts, GP consultation data
Give 3 major sources for routine data
Census
Health survey for England
NHS inpatient survey on patient experience
What are the advantages for routine data
Cheap Collected and available Standardised collection procedures Relatively comprehensive Wide range of recorded items Available for past years Need careful interpretation
What are the disadvantages for routine data
May not answer the question Incomplete ascertainment Variable quality Validity may be variable disease labelling may vary
Define age standardised death rates
How many people die each year and why
Define standardised mortality ratio
ratio between the observed number of deaths in a study population and the number of deaths would be expected
How do you calculate age standardised death rates
no. of observes death/ no. of the expected death if experienced the same age specific rates as standard population
