freq: List current frequency information.

Description Usage Format Details See Also Examples

Description

freq is a list of named numeric variables containing 11 frequencies:

Usage

1

Format

An object of class list of length 11.

Details

  1. the population size N

  2. the number of cases for which cond.true

  3. the number of cases for which cond.false

  4. the number of cases for which dec.pos

  5. the number of cases for which dec.neg

  6. the number of cases for which dec.cor

  7. the number of cases for which dec.err

  8. the number of true positives, or hits hi

  9. the number of false negatives, or misses mi

  10. the number of false positives, or false alarms fa

  11. the number of true negatives, or correct rejections cr

These frequencies are computed from basic parameters (contained in num) and computed by using comp_freq.

The list freq is the frequency counterpart to the list containing probability information prob.

Natural frequencies are always expressed in relation to the current population of size N.

Key relationships:

  1. to probabilities: A population of N individuals can be split into 2 subsets in 2 different ways:

    1. by condition: The frequency cond.true depends on the prevalence prev and the frequency cond.false depends on the prevalence's complement (1 - prev).

    2. by decision: The frequency dec.pos depends on the proportion of positive decisions ppod and the frequency dec.neg depends on the proportion of negative decisions (1 - ppod).

    The population size N is a free parameter (independent of the essential probabilities prev, sens, and spec).

    If N is unknown, a suitable minimum value can be computed by comp_min_N.

  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)

Visualizations of the current frequency information are provided by plot_tree and plot_mosaic.

See Also

comp_freq computes current frequency information; num contains basic numeric variables; init_num initializes basic numeric variables; prob contains current probability information; num contains basic numeric parameters; init_num initializes basic numeric parameters; txt contains current text information; init_txt initializes text information; pal contains current color information; init_pal initializes color information.

Other lists containing current scenario information: accu, num, pal, prob, txt

Examples

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freq <- comp_freq()  # => initialize freq to default parameters
freq                 # => show current values
length(freq)         # => 11

riskyr documentation built on Feb. 19, 2018, 5 p.m.