R/comp_prob_prob.R
comp_PPV.Rd
comp_PPV
computes the positive predictive value PPV
from 3 essential probabilities
prev
, sens
, and spec
.
comp_PPV(prev, sens, spec)
The condition's prevalence prev
(i.e., the probability of condition being TRUE
).
The decision's sensitivity sens
(i.e., the conditional probability of a positive decision
provided that the condition is TRUE
).
The decision's specificity value spec
(i.e., the conditional probability
of a negative decision provided that the condition is FALSE
).
The positive predictive value PPV
as a probability.
A warning is provided for NaN values.
comp_PPV
uses probabilities (not frequencies)
and does not round results.
comp_sens
and comp_NPV
compute related probabilities;
is_extreme_prob_set
verifies extreme cases;
comp_complement
computes a probability's complement;
is_complement
verifies probability complements;
comp_prob
computes current probability information;
prob
contains current probability information;
is_prob
verifies probabilities.
Other functions computing probabilities:
comp_FDR()
,
comp_FOR()
,
comp_NPV()
,
comp_accu_freq()
,
comp_accu_prob()
,
comp_acc()
,
comp_comp_pair()
,
comp_complement()
,
comp_complete_prob_set()
,
comp_err()
,
comp_fart()
,
comp_mirt()
,
comp_ppod()
,
comp_prob_freq()
,
comp_prob()
,
comp_sens()
,
comp_spec()
# (1) Ways to work:
comp_PPV(.50, .500, .500) # => PPV = 0.5
#> [1] 0.5
comp_PPV(.50, .333, .666) # => PPV = 0.499
#> [1] 0.4992504
# (2) Watch out for vectors:
prev <- seq(0, 1, .1)
comp_PPV(prev, .5, .5) # => without NaN values
#> [1] 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
comp_PPV(prev, 0, 1) # => with NaN values
#> Warning: PPV is NaN.
#> [1] NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN NaN
# (3) Watch out for extreme values:
comp_PPV(prev = 1, sens = 0, spec = .5) # => NaN, only mi: hi = 0 and fa = 0: PPV = 0/0 = NaN
#> Warning: PPV is NaN.
#> [1] NaN
is_extreme_prob_set(prev = 1, sens = 0, spec = .5) # => verifies extreme cases
#> Warning: Extreme case (prev = 1 & sens = 0):
#> N mi (FN) cases; 0 cond_false or dec_true cases; PPV = NaN.
#> [1] TRUE
comp_PPV(prev = 0, sens = .5, spec = 1) # => NaN, only cr: hi = 0 and fa = 0: PPV = 0/0 = NaN
#> Warning: PPV is NaN.
#> [1] NaN
is_extreme_prob_set(prev = 0, sens = .5, spec = 1) # => verifies extreme cases
#> Warning: Extreme case (prev = 0 & spec = 1):
#> N cr (TN) cases; 0 cond_true or dec_false cases; NPV = NaN.
#> [1] TRUE
comp_PPV(prev = .5, sens = 0, spec = 1) # => NaN, only cr: hi = 0 and fa = 0: PPV = 0/0 = NaN
#> Warning: PPV is NaN.
#> [1] NaN
is_extreme_prob_set(prev = .5, sens = 0, spec = 1) # => verifies extreme cases
#> Warning: Extreme case (sens = 0 & spec = 1):
#> 0 hi (TP) and 0 fa (FP) cases; 0 dec_pos cases; PPV = NaN.
#> [1] TRUE