ppod defines the proportion (baseline probability or rate) of a decision being positive (but not necessarily accurate/correct).

ppod

## Format

An object of class numeric of length 1.

## Details

Understanding or obtaining the proportion of positive decisions ppod:

• Definition: ppod is the (non-conditional) probability:

ppod = p(decision = positive)

or the base rate (or baseline probability) of a decision being positive (but not necessarily accurate/correct).

• Perspective: ppod classifies a population of N individuals by decision (ppod = dec_pos/N).

ppod is the "by decision" counterpart to prev (which adopts a "by condition" perspective).

• Alternative names: base rate of positive decisions (PR), proportion predicted or diagnosed, rate of decision = positive cases

• In terms of frequencies, ppod is the ratio of dec_pos (i.e., hi + fa) divided by N (i.e., hi + mi + fa + cr):

ppod = dec_pos/N = (hi + fa)/(hi + mi + fa + cr)

• Dependencies: ppod is a feature of the decision process or diagnostic procedure.

However, the conditional probabilities sens, mirt, spec, fart, PPV, and NPV also depend on the condition's prevalence prev.

## References

prob contains current probability information; comp_prob computes current probability information; num contains basic numeric parameters; init_num initializes basic numeric parameters; freq contains current frequency information; comp_freq computes current frequency information; is_prob verifies probabilities.
Other probabilities: FDR, FOR, NPV, PPV, acc, err, fart, mirt, prev, sens, spec
ppod <- .50     # sets a rate of positive decisions of 50%