Number of individuals for which the decision is positive.

dec_pos is a frequency that describes the number of individuals in the current population N for which the decision is positive (i.e., called or predicted cases).

dec_pos

Format

An object of class numeric of length 1.

Details

Key relationships:

1. to probabilities: The frequency of dec_pos individuals depends on the population size N and the decision's proportion of positive decisions ppod and is split further into two subsets of hi by the positive predictive value PPV and fa by the false detection rate FDR = 1 - PPV.

   Perspectives:

   1. by condition:

      The frequency dec_pos is determined by the population size N times the proportion of positive decisions ppod:

      dec_pos = N x ppod

   2. by decision:

      a. The frequency hi is determined by dec_pos times the positive predictive value PPV (aka. precision):

      hi = dec_pos x PPV

      b. The frequency fa is determined by dec_pos times the false detection rate FDR = (1 - PPV):

      fa = dec_pos x FDR = dec_pos x (1 - PPV)

2. to other frequencies: In a population of size N the following relationships hold:

   • N = cond_true + cond_false (by condition)

   • N = dec_pos + dec_neg (by decision)

   • N = dec_cor + dec_err (by correspondence of decision to condition)

   • N = hi + mi + fa + cr (by condition x decision)

Current frequency information is computed by comp_freq and contained in a list freq.

References

Consult Wikipedia: Confusion matrix for additional information.

See also

is_freq verifies frequencies; num contains basic numeric parameters; init_num initializes basic numeric parameters; freq contains current frequency information; comp_freq computes current frequency information; prob contains current probability information; comp_prob computes current probability information.

Other frequencies: N, cond_false, cond_true, cr, dec_cor, dec_err, dec_neg, fa, hi, mi

Examples

dec_pos <- 1000 * .33   # => sets dec_pos to 33% of 1000 = 330 cases.
is_freq(dec_pos)        # => TRUE
#> [1] TRUE
is_prob(dec_pos)        # => FALSE, as dec_pos is no probability (but ppod and PPV are)
#> [1] FALSE