PBayes: calculate a probability from Bayes Theorem.

In helophilus/ColsTools: A variety of convenience tools and short-cuts

Description

PBayes(Dis, TruePos = NULL, FalsePos= NULL, TrueNeg= NULL, FalseNeg= NULL)

Usage

PBayes(Dis, TruePos = NULL, FalsePos = NULL, TrueNeg = NULL,
  FalseNeg = NULL)

Arguments

Dis	the occurence of the disease
TruePos	proportion of true positives (sensitivity)
FalsePos	proportion of false positives
TrueNeg	proportion of true negatives (specificity)
FalseNeg	proportion of false negatives

Details

Three probabilities are required required: probability of someone having the disease and then two others, e.g. true positive and false positive probabilities.

Examples

# Say 1 in 10,000 have a disease. A test correctly identifies it 98% of the time
# but also suggests it is present when it isn't in 3% of cases. If someone gets
# positive result from the test, what's the probability they have the disease?

PBayes(1/10000, TruePos=0.98, FalsePos=0.03)

# answer is 0.33%

helophilus/ColsTools documentation built on May 30, 2019, 4:03 p.m.