N: Number of individuals in the population.

Description Usage Format Details References See Also Examples


N is a frequency that describes the number of individuals in the current population (i.e., the overall number of cases considered).




An object of class numeric of length 1.


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)

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


Consult Wikipedia: Statistical population 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: cond.false, cond.true, cr, dec.cor, dec.err, dec.neg, dec.pos, fa, hi, mi


N <- 1000   # => sets a population size of 1000
is_freq(N)  # => TRUE
is_prob(N)  # => FALSE (as N is no probability)

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