PASS Measurment: Scales, Numbers, Rates, Ratios And Risk Flashcards
What does descriptive epidemiology measure?
Disease burden
Incidence risk
Incidence rate
Prevalence rate
How frequent and quickly does it occur?
What does analytical epidemiology measure?
Effect
Risk ratio
Odds ratio
How and why does it occur?
What are the potential issues with analytical epidemiology?
Issues with measuring effect
Confounding - other factors associated?
Bias
Chance
Incidence meaning
Number of new cases
Prevalence meaning
Number of new cases
How to calculate incidence risk
Number of new cases during specified period
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Size of disease-free population at start
What is incidence rate?
How quickly disease occurs in a population
How do you calculate incidence rat?
Number of new cases during specified period
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Total of time each new person was observed
How do you calculate prevalence rate?
All new + pre-existing cases during given period
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Population during the same period
What is case-fatality rate?
Proportion of cases of a disease that are fatal within a specified period of time
What is mortality rate?
The number of deaths in a sample population, scaled to size of population per specified time
What does clinical medicine do?
Compares the risk of two diseases using signs and symptoms
What does public health policy do?
Prioritise the management of a disease with higher prevalence or mortality rate after clinical medicine has compared two diseases’ risks
What are risk ratio and odds ratio?
Effect measures that quantify the strength of the association between the exposure and the
event
What are risk ratios and odds ratios measured based on?
Incidence risks
Risk ratio calculation
Find proportions of different groups
Find the ratio between these proportions
Totals needed
Odds ratio calculation
Ratio of those with and without disease of each group (not total)
Find ratio between the two groups
Association when OR / RR > 1
Positive association
Association when OR / RR < 1
Negative association
Association when OR / RR = 1
No association
What is selection bias?
Sample is not representative of the population
What is confounding bias?
Effect of exposure on outcome is mixed by another factor
e.g. age not taken into account
What is recall bias?
Incomplete/inaccurate recollection of info by participants
Types of bias
Selection
Confounding
Recall
Publication
What type of error does bias cause?
Systematic error
What is publication bias?
When outcome of an experiment or study biases the decision to publish it or not
