Calculate the dependent variable (height or weight) using LMS parameters from anthropometric growth charts at a given Z score

lms_calc(z = 0, l = NA, m = NA, s = NA)

Arguments

z: Numeric or numerical vector of Z score(s) associated with a given percentile of the dependent variable. Default of 0 (i.e., 50th percentile).
l: Numeric or numerical vector of L parameter(s) from an anthropometric growth chart.
m: Numeric or numerical vector of M parameter(s) from an anthropometric growth chart.
s: Numeric or numerical vector of S parameter(s) from an anthropometric growth chart.

Value

Numeric or vector of numeric dependent variable value(s). Value is calculated according to: if l (rounded to 6 decimal places) is equal to 0, then = l*exp(s*z); otherwise = m*(1+l*s*z)^(1/l)).

Examples

# calculate weight (kg) for a male 2 year old at the 50th percentile of 
# weight for age and sex using CDC Growth Chart LMS parameters.
wtkg <- lms_calc(
z = qnorm(50/100), 
l = -0.2165012, 
m = 12.74154, 
s = 0.1081660
)

# calculate weight (kg) for male 2 year old at the 25th and 50th percentiles 
# of weight.
wtkg <- lms_calc(
z = c(qnorm(25/100),
qnorm(50/100)), 
l = -0.2165012, 
m = 12.74154, 
s = 0.1081660
)

# calculate weight (kg) for male at 50th percentile and female at 25th 
# percentile of weight.
wtkg <- lms_calc(
  z = c(0, qnorm(0.25)),
  l = c(-0.6213197, -1.0244713),
  m = c(14.40263, 13.94108),
  s = c(0.1118745, 0.1194917)
)