R/init_prob.R
fart.Rdfart defines a decision's false alarm rate
(or the rate of false positives): The conditional probability
of the decision being positive if the condition is FALSE.
fartAn object of class numeric of length 1.
Understanding or obtaining the false alarm rate fart:
Definition:
fart is the conditional probability
for an incorrect positive decision given that
the condition is FALSE:
fart = p(decision = positive | condition = FALSE)
or the probability of a false alarm.
Perspective:
fart further classifies
the subset of cond_false individuals
by decision (fart = fa/cond_false).
Alternative names:
false positive rate (FPR),
rate of type-I errors (alpha),
statistical significance level,
fallout
Relationships:
a. fart is the complement of the
specificity spec:
fart = 1 - spec
b. fart is the opposite conditional probability
-- but not the complement --
of the false discovery rate
or false detection rate FDR:
FDR = p(condition = FALSE | decision = positive)
In terms of frequencies,
fart is the ratio of
fa divided by cond_false
(i.e., fa + cr):
fart = fa/cond_false = fa/(fa + cr)
Dependencies:
fart is a feature of a decision process
or diagnostic procedure and a measure of
incorrect decisions (false positives).
However, due to being a conditional probability,
the value of fart is not intrinsic to
the decision process, but also depends on the
condition's prevalence value prev.
Consult Wikipedia for additional information.
comp_fart computes fart as the complement of spec
prob contains current probability information;
comp_prob computes current probability information;
num contains basic numeric parameters;
init_num initializes basic numeric parameters;
comp_freq computes current frequency information;
is_prob verifies probabilities.
Other probabilities:
FDR,
FOR,
NPV,
PPV,
acc,
err,
mirt,
ppod,
prev,
sens,
spec
fart <- .25 # sets a false alarm rate of 25%
fart <- 25/100 # (decision = positive) for 25 out of 100 people with (condition = FALSE)
is_prob(fart) # TRUE
#> [1] TRUE