Critical Numbers Flashcards
Define prevalence
Probability of having a condition at a given time point
Define incidence
Probability of getting a condition within a specified time period
Sensitivity=
TP/ (TP+ FN)
Define sensitivity
Have the condition and correctly identified
Specificity=
TN / (TN + FP)
Define specificity
No condition and are correctly identified
Risk difference =
Risk of outcome if treatment given - risk of outcome if no treatment given
What is the average rate of change of incidence probability over time?
Incidence rate
What is the instantaneous rate of change of incidence probability over time?
Hazard rate
Define NNT
Number of ppl you need to treat in order to prevent one outcome
NNT =
1/ |RD|
RD should be negative
Defien NNH
Number of ppl you need to treat in order to cause the harmful outcome
NNH =
1/ RD
RD should be positive
What does a RR of 1 mean?
No effect/ association
What does a RR > 1 mean?
Positive association, risk factor
What does a RR < 1 mean?
Negative association, protective factor/ effect
What does a RD of 0 mean?
No effect/ association
What does a RD > 0 mean?
Positive association, risk factor
What does a RD < 0 mean?
Negative association, protective factor/effect
Probability =
cases/ #population
Odds =
cases/ #non-cases
Define absolute risk
Likelihood of health effect occurring under specific conditions
Define relative risk
Likelihood of an event occurring in a group of ppl compared with another group w/ different behaviours, physical conditions and env
Define bias
Systematic error in the design of the study or how the measurements are taken
What is a cohort study?
The incidence of the disease in EXPOSED group is compared w/ incidence in UNEXPOSED group
What is an RCT?
Compares the incidence of disease in the treatment group with the control group
What is a case-controlled study?
Prevalence of past exposure among cases and control is compared
What is a cross-sectional study?
Outcome and exposures measured simultaneously in a given population
