NEWS

merTools 0.3.0

• Improve handling of formulas. If the original merMod has functions specified in the formula, the draw and wiggle functions will check for this and attempt to respect these variable transformations. Where this is not possible a warning will be issued. Most common transformations are respected as long as the the original variable is passed untransformed to the model.
• Change the calculations of the residual variance. Previously residual variance was used to inflate both the variance around the fixed parameters and around the predicted values themselves. This was incorrect and resulted in overly conservative estimates. Now the residual variance is appropriately only used around the final predictions
• Rebuilt the readme.md to include new information about new features
• New option for predictInterval that allows the user to return the full interval, the fixed component, the random component, or the fixed and each random component separately for each observation
• Fixed a bug with slope+intercept random terms that caused a miscalculation of the random component
• Add comparison to rstanarm to the Vignette
• Make expectedRank output more tidy like and allow function to calculate expected rank for all terms at once
• Note, this breaks the API by changing the names of the columns in the output of this function
• Remove tests that test for timing to avoid issues with R-devel JIT compiler
• Remove plyr and replace with dplyr
• Fix issue #62 varList will now throw an error if == is used instead of =
• Fix issue #54 predictInterval did not included random effects in calculations when newdata had more than 1000 rows and/or user specified parallel=TRUE. Note: fix was to disable the .paropts option for predictInterval ... user can still specify for temporary backward compatibility but this should be either removed or fixed in the permanent solution.
• Fix issue #53 about problems with predictInterval when only specific levels of a grouping factor are in newdata with the colon specification of interactions
• Fix issue #52 ICC wrong calculations ... we just needed to square the standard deviations that we pulled

merTools 0.2.1

• Fix dependency on lme4 to ensure compatibility with latest changes.

merTools 0.2

Bug fixes

• Coerce dplyr tbl and tbl_df objects to data.frames when they are passed to predictInterval and issue a warning
• Try to coerce other data types passed to newdata in predictInterval before failing if coercion is unsuccessful
• Numeric stabilization of unit tests by including seed values for random tests
• Fix handling of models with nested random effect terms (GitHub #47)
• Fix vignette images

New Functionality

• Substantial performance enhancement for predictInterval which includes better handling of large numbers of parameters and simulations, performance tweaks for added speed (~10x), and parallel backend support (currently not optimized)
• Add support for probit models and limited support for other glmm link functions, with warning (still do not know how to handle sigma parameter for these)
• Add ability for user-specified seed for reproducibility
• Add support for blmer objects from the blme package
• Add a merModList object for lists of merMod objects fitted to subsets of a dataset, useful for imputation or for working with extremely large datasets
• Add a print method for merModList to mimic output of summary.merMod
• Add a VarCorr method for merModList
• Add new package data to demonstrate replication from selected published texts on multilevel modeling using different software (1982 High School and Beyond Survey data)

Other changes

• Changed the default n.sims for the predictInterval function from 100 to 1,000 to give better coverage and reflect performance increase
• Changed the default for level in predictInterval to be 0.8 instead of 0.95 to reflect that 0.95 prediction intervals are more conservative than most users need

Future changes

• For the next release (1.0) we are considering a permanent switch to C++ RMVN sampler courtesy of Giri Gopalan 's excellent FastGP package

merTools 0.1

• Initial release

New Functions

• Provides predictInterval to allow prediction intervals from glmer and lmer objects
• Provides FEsim and REsim to extract distributions of model parameters
• Provides shinyMer an interactive shiny application for exploring lmer and glmer models
• Provides expectedRank function to interpret the ordering of effects
• Provides REimpact to simulate the impact of grouping factors on the outcome
• Provides draw function to allow user to explore a specific observation
• Provides wiggle function for user to build a simulated set of counterfactual cases to explore