Convert WHO z-scores/centiles to anthro measurements (generic)

Get values of a specified measurement for a given WHO centile/z-score and growth standard pair (e.g. length vs. age) and sex over a specified grid

who_centile2value(
  x,
  p = 50,
  x_var = "agedays",
  y_var = "lenhtcm",
  sex = "Female",
  data = NULL
)

who_zscore2value(
  x,
  z = 0,
  y_var = "lenhtcm",
  x_var = "agedays",
  sex = "Female",
  data = NULL
)

Arguments

x

vector specifying the values of x over which to provide the centiles for y

p

centile or vector of centiles at which to compute values (a number between 0 and 100 - 50 is median)

x_var

x variable name (typically "agedays") - see details

y_var

y variable name (typically "htcm" or "wtkg") that specifies which variable of values should be returned for the specified value of q - see details

sex

"Male" or "Female"

data

optional data frame that supplies any of the other variables provided to the function

z

z-score or vector of z-scores at which to compute values

Details

for all supported pairings of y_var and x_var , type names(who_coefs)

See also

who_value2centile, who_value2zscore

Examples

# median height vs. age for females
x <- seq(0, 365, by = 7)
med <- who_centile2value(x)
plot(x, med, xlab = "age in days", ylab = "median female height (cm)")


# 99th percentile of weight vs. age for males from age 0 to 1461 days
dat <- data.frame(x = rep(seq(0, 1461, length = 100), 2),
  sex = rep(c("Male", "Female"), each = 100))
dat$p99 <- who_centile2value(x, p = 99, y_var = "wtkg", sex = sex, data = dat)
lattice::xyplot(kg2lb(p99) ~ days2years(x), groups = sex, data = dat,
  ylab = "99th percentile weight (pounds) for males",
  xlab = "age (years)", auto.key = TRUE)