Support for bootstrapping models with a mixture of correlation struct…

…ures (#577)

* Loosen type constraint on MixedModelsBootstrap.λ

Changing the type constraint on λ fixes problems when bootstrapping models
with a mixture of zerocorr (Diagonal) and non zerocorr (LowerTriangular)
RE representations. We also remove the type constraint on the parent, i.e.
 internal  storage within LowerTriangular|Diagonal so that we can better
support more types in the future. As a pleasant side effect, this makes
the type parameterization easier.

* Patch bump + NEWS

NEWS.md

@@ -1,3 +1,7 @@
+MixedModels v4.4.1 Release Notes
+========================
+* Fix type parameterization in MixedModelsBootstrap to support models with a mixture of correlation structures (i.e. `zerocorr` in some but not all RE terms) [#577]
+
 MixedModels v4.4.0 Release Notes
 ========================
 * Add a constructor for the abstract type `MixedModel` that delegates to `LinearMixedModel` or `GeneralizedLinearMixedModel`. [#572]
@@ -306,3 +310,4 @@ Package dependencies
 [#570]: https://github.com/JuliaStats/MixedModels.jl/issues/570
 [#572]: https://github.com/JuliaStats/MixedModels.jl/issues/572
 [#573]: https://github.com/JuliaStats/MixedModels.jl/issues/573
+[#577]: https://github.com/JuliaStats/MixedModels.jl/issues/577

Project.toml

@@ -1,7 +1,7 @@
 name = "MixedModels"
 uuid = "ff71e718-51f3-5ec2-a782-8ffcbfa3c316"
 author = ["Phillip Alday <[email protected]>", "Douglas Bates <[email protected]>", "Jose Bayoan Santiago Calderon <[email protected]>"]
-version = "4.4.0"
+version = "4.4.1"
 
 [deps]
 Arrow = "69666777-d1a9-59fb-9406-91d4454c9d45"

src/bootstrap.jl

@@ -28,7 +28,7 @@ and correlations of the random-effects terms.
 """
 struct MixedModelBootstrap{T<:AbstractFloat} <: MixedModelFitCollection{T}
     fits::Vector
-    λ::Vector{<:Union{LowerTriangular{T,Matrix{T}},Diagonal{T,Vector{T}}}}
+    λ::Vector{Union{LowerTriangular{T},Diagonal{T}}}
     inds::Vector{Vector{Int}}
     lowerbd::Vector{T}
     fcnames::NamedTuple

test/bootstrap.jl

@@ -112,6 +112,14 @@ end
         @test typeof(pbzc) == MixedModelBootstrap{Float16}
     end
 
+    @testset "zerocorr + not zerocorr" begin
+        form_zc_not = @formula(rt_trunc ~ 1 + spkr * prec * load +
+                                         (1 + spkr + prec + load | subj) +
+                                 zerocorr(1 + spkr + prec + load | item))
+        fmzcnot = fit(MixedModel, form_zc_not, dataset(:kb07))
+        pbzcnot = parametricbootstrap(MersenneTwister(42), 2, fmzcnot, Float16)
+    end
+
     @testset "Bernoulli simulate! and GLMM boostrap" begin
         contra = dataset(:contra)
         # need a model with fast=false to test that we only