# sens: The sensitivity (or hit rate) of a decision process or... In riskyr: Rendering Risk Literacy more Transparent

## Description

`sens` defines a decision's sensitivity (or hit rate) value: The conditional probability of the decision being positive if the condition is `TRUE`.

## Usage

 `1` ```sens ```

## Format

An object of class `numeric` of length 1.

## Details

Understanding or obtaining the sensitivity `sens` (or hit rate `HR`):

• Definition: `sens` is the conditional probability for a (correct) positive decision given that the condition is `TRUE`:

`sens = p(decision = positive | condition = TRUE)`

or the probability of correctly detecting true cases (`condition = TRUE`).

• Perspective: `sens` further classifies the subset of `cond_true` individuals by decision (`sens = hi/cond_true`).

• Alternative names: true positive rate (`TPR`), hit rate (`HR`), probability of detection, `power = 1 - beta`, `recall`

• Relationships:

a. `sens` is the complement of the miss rate `mirt` (aka. false negative rate `FNR` or the rate of Type-II errors):

`sens = (1 - miss rate) = (1 - FNR)`

b. `sens` is the opposite conditional probability – but not the complement – of the positive predictive value `PPV`:

`PPV = p(condition = TRUE | decision = positive)`

• In terms of frequencies, `sens` is the ratio of `hi` divided by `cond_true` (i.e., `hi + mi`):

`sens = hi/cond_true = hi/(hi + mi)`

• Dependencies: `sens` is a feature of a decision process or diagnostic procedure and a measure of correct decisions (true positives).

Due to being a conditional probability, the value of `sens` is not intrinsic to the decision process, but also depends on the condition's prevalence value `prev`.

## References

`comp_sens` computes `sens` as the complement of `mirt`; `prob` contains current probability information; `comp_prob` computes current probability information; `num` contains basic numeric parameters; `init_num` initializes basic numeric parameters; `comp_freq` computes current frequency information; `is_prob` verifies probabilities.

Other probabilities: `FDR`, `FOR`, `NPV`, `PPV`, `acc`, `err`, `fart`, `mirt`, `ppod`, `prev`, `spec`

Other essential parameters: `cr`, `fa`, `hi`, `mi`, `prev`, `spec`

## Examples

 ```1 2 3``` ```sens <- .85 # sets a sensitivity value of 85% sens <- 85/100 # (decision = positive) for 85 out of 100 people with (condition = TRUE) is_prob(sens) # TRUE ```

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