Description Usage Arguments Value Author(s) References See Also Examples

The `daz()`

function calculated the
"Development for Age Z-score".
The DAZ represents a child's D-score after adjusting
for age by an external age-conditional reference.
The `zad()`

is the inverse of `daz()`

: Given age and
the Z-score, it finds the raw D-score.

1 2 3 | ```
daz(d, x = as.numeric(names(d)), reference = get_reference(), dec = 3)
zad(z, x = as.numeric(names(z)), reference = get_reference(), dec = 2)
``` |

`d` |
Vector of D-scores |

`x` |
Vector of ages (decimal age) |

`reference` |
A |

`dec` |
The number of decimals (default |

`z` |
Vector of standard deviation scores (DAZ) |

The `daz()`

function return a named vector with
Z-scores with `length(d)`

elements

The `zad()`

function returns a vector with D-scores
with `length(z)`

elements.

Stef van Buuren 2020

Cole TJ, Green PJ (1992). Smoothing reference centile curves: The LMS method and penalized likelihood. Statistics in Medicine, 11(10), 1305-1319.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | ```
# using gcdg-reference
daz(d = c(35, 50), x = c(0.5, 1.0))
# using Dutch reference
daz(d = c(35, 50), x = c(0.5, 1.0), reference = get_reference("dutch"))
# population median at ages 0.5, 1 and 2 years, gcdg reference
zad(z = rep(0, 3), x = c(0.5, 1, 2))
# population median at ages 0.5, 1 and 2 years, dutch reference
zad(z = rep(0, 3), x = c(0.5, 1, 2), reference = get_reference("dutch"))
# percentiles of D-score reference
g <- expand.grid(age = seq(0.1, 2, 0.1), p = c(0.1, 0.5, 0.9))
d <- zad(z = qnorm(g$p), x = g$age)
matplot(
x = matrix(g$age, ncol = 3), y = matrix(d, ncol = 3), type = "l",
lty = 1, col = "blue", xlab = "Age (years)", ylab = "D-score"
)
``` |

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