Gets predicted values based on a new dataframe for lmer models
Source:R/predict-lmer.R
      dh.predictLmer.RdCurrently there is no predict method for lmer models within DataSHIELD.
This function replicates this, by calculating predicted values for fixed
effects based on the model coefficients. Standard errors are returned for
individual cohorts but yet for pooled models.
Arguments
- model
- Model object returned by ds.lmerSLMA. 
- new_data
- Tibble or data frame containing values for variables in - modelat which to predict values of the outcome. The column names in- new_datamust be identical to those in- model, and all variables included in- modelmust be present in- new_data.
- coh_names
- Please specify 'conns' instead. Vector of cohort names. These must be in the order that cohorts were specified in - model.
See also
Other trajectory functions: 
dh.lmeMultPoly(),
dh.makeAgePolys(),
dh.makeLmerForm(),
dh.trimPredData(),
dh.zByGroup()