sitar - v1.5.0

Changes in Version 1.5.0

o Now depends on R >= 4.1.0.

o update.sitar has been streamlined and should now be faster.

o plot.sitar now handles par() parameters for combined distance-velocity plots differently - a breaking change. Instead of entries for the y2 axis being collected in parameter 'y2par', the entries for both y1 and y2 axes are now combined - see examples.

o Other breaking changes in plot.sitar - the argument 'design' has been removed, and the first three tibble column names returned from the helper functions 'plot_d' etc are now the names of x, y and id from the original sitar call.

o A new function getDV returns peak velocity and age at peak velocity for individuals, including those with a truncated growth curve - see the example.

o predict.sitar now calculates velocity by differentiating each point (as dy/dx) rather than differentiating the mean spline curve. This means it handles velocities at a single age, and can return predicted distance and velocity for both levels 0 and 1.

o In addition the arguments xfun and yfun in predict.sitar have been removed - a breaking change.

o The d random effect now has an alternative parameterisation, controlled by the sitar argument d.adjusted. The age slope d is the regression coefficient of y on x, and when d.adjusted = TRUE x is first adjusted for random effects b and c, reflecting individual developmental age rather than chronological age. The default d.adjusted = FALSE appears on limited testing to fit better.

- R
Published by statist7 12 months ago

sitar - v1.4.0

Changes in v1.4.0

o plot.sitar plots multiple curves for options 'd' and 'v' when the model includes categorical variables.

o plot.sitar option 'V' returns velocity curves that are both faster and more accurate.

o xyadj is extended to convert velocity from/to the mean.

o If df > 1 and random = 'a+b+c+d' then fixed = 'a+b+c' by default.

o If df = 1 in sitar then fixed effects b and d are excluded.

o The function identity is now recognised by ifun.

o Bugs in update.sitar and BICadj relating to the keep.data argument are fixed.

o An egregious bug with factor covariates in predict.sitar is fixed.

o The fitnlme function in sitar is simplified.

o A bug in ob_convertr2 handling missing data is fixed.

- R
Published by statist7 about 3 years ago

sitar - v1.3.0

Changes in Version 1.3.0

o Typos in the berkeley dataset reported as issue #7 are fixed.

o The argument keep.data is added to sitar with default TRUE. This saves a copy of the data in the object, which avoids some environment issues.

o obconvertr is rewritten and extended with the addition of obconvertr2, and is now much faster. As a result the interface is altered - a breaking change.

o The dataset deren example is updated to match the revised ob_convertr.

- R
Published by statist7 almost 4 years ago

sitar - 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.

- R
Published by statist7 about 5 years ago