NPV {riskyr} | R Documentation |
The negative predictive value of a decision process or diagnostic procedure.
Description
NPV
defines some decision's negative predictive value (NPV):
The conditional probability of the condition being FALSE
provided that the decision is negative.
Usage
NPV
Format
An object of class numeric
of length 1.
Details
Understanding or obtaining the negative predictive value NPV
:
Definition:
NPV
is the conditional probability for the condition beingFALSE
given a negative decision:NPV = p(condition = FALSE | decision = negative)
or the probability of a negative decision being correct.
Perspective:
NPV
further classifies the subset ofdec_neg
individuals by condition (NPV = cr/dec_neg = cr/(mi + cr)
).Alternative names: true omission rate
Relationships:
a.
NPV
is the complement of the false omission rateFOR
:NPV = 1 - FOR
b.
NPV
is the opposite conditional probability – but not the complement – of the specificityspec
:spec = p(decision = negative | condition = FALSE)
In terms of frequencies,
NPV
is the ratio ofcr
divided bydec_neg
(i.e.,cr + mi
):NPV = cr/dec_neg = cr/(cr + mi)
Dependencies:
NPV
is a feature of a decision process or diagnostic procedure and – similar to the specificityspec
– a measure of correct decisions (negative decisions that are actually FALSE).However, due to being a conditional probability, the value of
NPV
is not intrinsic to the decision process, but also depends on the condition's prevalence valueprev
.
References
Consult Wikipedia for additional information.
See Also
comp_NPV
computes NPV
;
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
,
PPV
,
acc
,
err
,
fart
,
mirt
,
ppod
,
prev
,
sens
,
spec
Examples
NPV <- .95 # sets a negative predictive value of 95%
NPV <- 95/100 # (condition = FALSE) for 95 out of 100 people with (decision = negative)
is_prob(NPV) # TRUE