biostats Flashcards
What is the definition of sensitivity?
Probability of a disease person testing positive
What is the formula for sensitivity?
TP/TP+FN
What is the definition of specificity?
Probability of a non diseases person testing negative
What is the formula for specificity?
TN/TN+FP
What is the definition for positive predictive value?
Probability that the disease is present when you have a positive result
What is the definition for negative predictive value?
Probability that the disease is absent when you have a negative result
What is the definition for positive likelihood ratio?
Likelihood of having a disease with a positive test result
What is the definition of negative likelihood ratio?
Likelihood of not having a disease with a negative test result
What is the formula for positive likelihood ratio?
sensitivity/ 1- specificity
What is the formula for negative likelihood ratio?
1-sensitivity/specificity
What is primary prevention?
Educating and screening a patient to prevent disease. Action taken before patient develops disease
What is secondary prevention?
Attempt to halting progression of disease
What type of study should you calculate odds ratio?
case control studies
What type of study should you calculate relative risk?
cohort study
What is the definition of relative risk?
Risk of developing disease in exposed group/ risk of developing disease in the unexposed group
What is the formula for relative risk?
(a/a+b)/(c/c+d)
What is the formula for NNT?
1/ARR
What is the formula of ARR?
(Events from controlled group) - (Events from treatment group)