R/comp_prob_prob.R
comp_PPV.Rdcomp_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