Version 1.2.0
Changes in Version 1.2.0
o The dataset deren is added for use with ob_convertr.
o A function ob_convertr is added which converts child prevalence rates for
underweight, overweight or obesity from one reference cutoff to another.
o dfpower is extended to include fixed effects for a-b-c-d as well as spline
degrees of freedom and powers of x and y. It also now passes the control
arg if set and refits the target object.
o A major extension to the SITAR model is to add a fourth random effect
called d, which is the age slope. It allows the simple random intercept
random slope model to be fitted, but it also extends the usual SITAR model by
allowing the adult portion of the growth curve to vary in slope.
o A breaking change fixes the prediction and plotting of mean curves for models
with fewer fixed effects than random effects, e.g. random = 'a + b + c' and
fixed = 'a + b'. The mean curve now corresponds to the mean of the fitted
random effects, whereas before it did not.
o The fitted SITAR model now includes an element 'constants', a data frame
giving the mean values of a-b-c-d indexed by unique levels of covariates
where fitted. Can be useful for models with complex fixed effects.
o Two functions optimal_design and nagegp are added for the optimal design of
group reference centile studies - see Cole (Statistical Methods in Medical
Research, 2020). A vignette has also been added describing how to use them.
o The cdc2000 and iotf datasets are added.
o The who0607 dataset is added, extending who06 to age 19 for height, weight
and BMI.
o The ukwhoterm dataset is added, similar to ukwhopt but excluding infants
born preterm.
o The ukwhopt dataset is extended to cover age 26 weeks gestation to 20 years.
o apv_se is updated to work with the latest version of rtidy.
o LMS2z is extended to handle disjunct references, where the centiles have a
break or disjunction. Sex is also checked for more carefully.
o sitar has a new argument pdDiag, which forces the random effects covariance
matrix to be diagonal. Convergence can be much quicker, though the model may
fit less well.
o pdLMS density calculation corrected.
o In plot.sitar, transformations of x / y using xfun / yfun are now applied
after back-transforming x / y to their original scales.
o getPeakTrough algorithm improved, and takeoff argument added for use with
velocity curves to identify age at takeoff.
o Methods getPeak, getTrough and getTakeoff are added as special cases of
getPeakTrough.