# dec_pos: Number of individuals for which the decision is positive. In riskyr: Rendering Risk Literacy more Transparent

## Description

`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).

## Usage

 `1` ```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.

`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

 ```1 2 3``` ```dec_pos <- 1000 * .33 # => sets dec_pos to 33% of 1000 = 330 cases. is_freq(dec_pos) # => TRUE is_prob(dec_pos) # => FALSE, as dec_pos is no probability (but ppod and PPV are) ```

riskyr documentation built on Jan. 3, 2019, 1:06 a.m.