Flashcards in Stats equations to memorise Deck (16):
How do you calculate NNT?
(ARR = CER-EER)
How to calculate sensitivity?
Sensitivity = TP/(TP+FN)
How to calculate specificity?
Specificity = TN/(TN+FP)
How to calculate positive predictive value?
PPV = TP/(TP+FP)
How to calculate negative predictive value?
NPP = TN/(TN+FN)
How to calculate likelihood ratio for a positive result?
Likelihood +ive = sensitivity/(1-specificity)
How to calculate likelihood ratio for a negative result?
Liklihood -ive = (1-sensitivty)/specificity)
How to calculate odds ratio?
a) Odds of outcome in cases = number with/number without
b) Odds of outcome in controls = number with/number without
c) Odds ratio = a/b
What study design usually gives its answer as odds ratio?
How do you calculate relative risk reduction?
Absolute risk change/control event rate
I.e., RRR = ARR/CER
How to calculate risk of an outcome in a group?
Number of people developing the condition as a proportion of the total.
Eg, 1000 people exposed to a risk factor. 200 of them die. Risk = 200/1000 = 0.2
How do you calculate standard error?
SE = standard deviation/square root of n.
False negative rate = ?
False negative rate = 1-sensitivity
Calculate experimental event ratio or control event ratio? What is it expressed as?
Number who had the outcome/total number treated.
Expressed as a decimal or as a %
How to calculate relative risk?