entropy_k {Rage}

Calculate Keyfitz's entropy from a trajectory of age-specific survivorship

Description

Calculate Keyfitz's entropy from a vector of age-specific survivorship (lx).

Usage

entropy_k(lx, trapeze = FALSE, ...)

Arguments

lx

Either a survivorship trajectory (a vector of monotonically-declining values in the interval [0,1]), or submatrix U from a matrix population model.

trapeze

A logical argument indicating whether the composite trapezoid approximation should be used for approximating the definite integral.

...

Additional variables passed to 'mpm_to_lx' if data are supplied as a matrix

Value

Keyfitz's life table entropy.

Warning

Note that this function may produce unexpected results if used on partial survivorship trajectories. In addition, it is sensitive to the length of the survivorship vector. We direct users to the function 'shape_surv' which is relatively robust to these issues.

Author(s)

Owen R. Jones <[e-mail]>

Roberto Salguero-Gomez <[e-mail]>

References

Keyfitz, N. 1977. Applied Mathematical Demography. New York: Wiley.

Demetrius, L., & Gundlach, V. M. 2014. Directionality theory and the entropic principle of natural selection. Entropy 16: 5428-5522.

See Also

Other life history traits: entropy_d(), gen_time(), life_expect_mean(), longevity(), net_repro_rate(), repro_maturity, shape_rep(), shape_surv()

Examples

data(mpm1)

# derive lx trajectory, starting from stage 2
lx <- mpm_to_lx(mpm1$matU, start = 2)

# calculate Keyfitz' entropy
entropy_k(lx)

# use trapezoid approximation for definite integral
entropy_k(lx, trapeze = TRUE)

# calculate directly from the matrix
entropy_k(mpm1$matU)