diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 4867c046..b96ee980 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -14,7 +14,7 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - '1.0'
+          - '1.3'
           - '1'
           - 'nightly'
         os:
diff --git a/Project.toml b/Project.toml
index c6298096..05009511 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "MCMCDiagnosticTools"
 uuid = "be115224-59cd-429b-ad48-344e309966f0"
 authors = ["David Widmann"]
-version = "0.1.5"
+version = "0.2.0"
 
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"
@@ -23,7 +23,7 @@ MLJModelInterface = "1.6"
 SpecialFunctions = "0.8, 0.9, 0.10, 1, 2"
 StatsBase = "0.33"
 Tables = "1"
-julia = "1"
+julia = "1.3"
 
 [extras]
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
diff --git a/docs/Project.toml b/docs/Project.toml
index 1ff9375c..ad15f1d3 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -8,7 +8,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 
 [compat]
 Documenter = "0.27"
-MCMCDiagnosticTools = "0.1"
+MCMCDiagnosticTools = "0.2"
 MLJBase = "0.19, 0.20, 0.21"
 MLJXGBoostInterface = "0.1, 0.2, 0.3"
 julia = "1.3"
diff --git a/src/discretediag.jl b/src/discretediag.jl
index ddf17248..72e9ca6e 100644
--- a/src/discretediag.jl
+++ b/src/discretediag.jl
@@ -372,7 +372,7 @@ function discretediag_sub(
     start_iter::Int,
     step_size::Int,
 )
-    num_iters, num_vars, num_chains = size(c)
+    num_iters, num_chains, num_vars = size(c)
 
     ## Between-chain diagnostic
     length_results = length(start_iter:step_size:num_iters)
@@ -384,7 +384,7 @@ function discretediag_sub(
         pvalue=Vector{Float64}(undef, num_vars),
     )
     for j in 1:num_vars
-        X = convert(AbstractMatrix{Int}, c[:, j, :])
+        X = convert(AbstractMatrix{Int}, c[:, :, j])
         result = diag_all(X, method, nsim, start_iter, step_size)
 
         plot_vals_stat[:, j] .= result.stat ./ result.df
@@ -403,7 +403,7 @@ function discretediag_sub(
     )
     for k in 1:num_chains
         for j in 1:num_vars
-            x = convert(AbstractVector{Int}, c[:, j, k])
+            x = convert(AbstractVector{Int}, c[:, k, j])
 
             idx1 = 1:round(Int, frac * num_iters)
             idx2 = round(Int, num_iters - frac * num_iters + 1):num_iters
@@ -423,14 +423,16 @@ function discretediag_sub(
 end
 
 """
-    discretediag(chains::AbstractArray{<:Real,3}; frac=0.3, method=:weiss, nsim=1_000)
+    discretediag(samples::AbstractArray{<:Real,3}; frac=0.3, method=:weiss, nsim=1_000)
 
-Compute discrete diagnostic where `method` can be one of `:weiss`, `:hangartner`,
+Compute discrete diagnostic on `samples` with shape `(draws, chains, parameters)`.
+
+`method` can be one of `:weiss`, `:hangartner`,
 `:DARBOOT`, `:MCBOOT`, `:billinsgley`, and `:billingsleyBOOT`.
 
 # References
 
-Benjamin E. Deonovic, & Brian J. Smith. (2017). Convergence diagnostics for MCMC draws of a categorical variable. 
+Benjamin E. Deonovic, & Brian J. Smith. (2017). Convergence diagnostics for MCMC draws of a categorical variable.
 """
 function discretediag(
     chains::AbstractArray{<:Real,3}; frac::Real=0.3, method::Symbol=:weiss, nsim::Int=1000
diff --git a/src/ess.jl b/src/ess.jl
index ee06b13c..d385ad8d 100644
--- a/src/ess.jl
+++ b/src/ess.jl
@@ -201,7 +201,7 @@ end
     )
 
 Estimate the effective sample size and the potential scale reduction of the `samples` of
-shape (draws, parameters, chains) with the `method` and a maximum lag of `maxlag`.
+shape `(draws, chains, parameters)` with the `method` and a maximum lag of `maxlag`.
 
 See also: [`ESSMethod`](@ref), [`FFTESSMethod`](@ref), [`BDAESSMethod`](@ref)
 """
@@ -212,8 +212,8 @@ function ess_rhat(
 )
     # compute size of matrices (each chain is split!)
     niter = size(chains, 1) ÷ 2
-    nparams = size(chains, 2)
-    nchains = 2 * size(chains, 3)
+    nparams = size(chains, 3)
+    nchains = 2 * size(chains, 2)
     ntotal = niter * nchains
 
     # do not compute estimates if there is only one sample or lag
@@ -238,7 +238,7 @@ function ess_rhat(
     rhat = Vector{T}(undef, nparams)
 
     # for each parameter
-    for (i, chains_slice) in enumerate((view(chains, :, i, :) for i in axes(chains, 2)))
+    for (i, chains_slice) in enumerate(eachslice(chains; dims=3))
         # check that no values are missing
         if any(x -> x === missing, chains_slice)
             rhat[i] = missing
diff --git a/src/gelmandiag.jl b/src/gelmandiag.jl
index 87626672..001ab282 100644
--- a/src/gelmandiag.jl
+++ b/src/gelmandiag.jl
@@ -1,14 +1,15 @@
 function _gelmandiag(psi::AbstractArray{<:Real,3}; alpha::Real=0.05)
-    niters, nparams, nchains = size(psi)
+    niters, nchains, nparams = size(psi)
     nchains > 1 || error("Gelman diagnostic requires at least 2 chains")
 
     rfixed = (niters - 1) / niters
     rrandomscale = (nchains + 1) / (nchains * niters)
 
-    S2 = map(Statistics.cov, (view(psi, :, :, i) for i in axes(psi, 3)))
+    # `eachslice(psi; dims=2)` breaks type inference 
+    S2 = map(x -> Statistics.cov(x; dims=1), (view(psi, :, i, :) for i in axes(psi, 2)))
     W = Statistics.mean(S2)
 
-    psibar = dropdims(Statistics.mean(psi; dims=1); dims=1)'
+    psibar = dropdims(Statistics.mean(psi; dims=1); dims=1)
     B = niters .* Statistics.cov(psibar)
 
     w = LinearAlgebra.diag(W)
@@ -52,9 +53,10 @@ function _gelmandiag(psi::AbstractArray{<:Real,3}; alpha::Real=0.05)
 end
 
 """
-    gelmandiag(chains::AbstractArray{<:Real,3}; alpha::Real=0.95)
+    gelmandiag(samples::AbstractArray{<:Real,3}; alpha::Real=0.95)
 
-Compute the Gelman, Rubin and Brooks diagnostics [^Gelman1992] [^Brooks1998].  Values of the
+Compute the Gelman, Rubin and Brooks diagnostics [^Gelman1992] [^Brooks1998] on `samples`
+with shape `(draws, chains, parameters)`.  Values of the
 diagnostic’s potential scale reduction factor (PSRF) that are close to one suggest
 convergence.  As a rule-of-thumb, convergence is rejected if the 97.5 percentile of a PSRF
 is greater than 1.2.
@@ -70,12 +72,13 @@ function gelmandiag(chains::AbstractArray{<:Real,3}; kwargs...)
 end
 
 """
-    gelmandiag_multivariate(chains::AbstractArray{<:Real,3}; alpha::Real=0.05)
+    gelmandiag_multivariate(samples::AbstractArray{<:Real,3}; alpha::Real=0.05)
 
-Compute the multivariate Gelman, Rubin and Brooks diagnostics.
+Compute the multivariate Gelman, Rubin and Brooks diagnostics on `samples` with shape
+`(draws, chains, parameters)`.
 """
 function gelmandiag_multivariate(chains::AbstractArray{<:Real,3}; kwargs...)
-    niters, nparams, nchains = size(chains)
+    niters, nchains, nparams = size(chains)
     if nparams < 2
         error(
             "computation of the multivariate potential scale reduction factor requires ",
diff --git a/src/rafterydiag.jl b/src/rafterydiag.jl
index 8f34f0b8..a6960838 100644
--- a/src/rafterydiag.jl
+++ b/src/rafterydiag.jl
@@ -38,7 +38,7 @@ function rafterydiag(
         dichot = Int[(x .<= StatsBase.quantile(x, q))...]
         kthin = 0
         bic = 1.0
-        local test , ntest
+        local test, ntest
         while bic >= 0.0
             kthin += 1
             test = dichot[1:kthin:nx]
diff --git a/src/rstar.jl b/src/rstar.jl
index 2def08d4..7eb61c9b 100644
--- a/src/rstar.jl
+++ b/src/rstar.jl
@@ -1,15 +1,91 @@
 """
     rstar(
-        rng=Random.GLOBAL_RNG,
-        classifier,
-        samples::AbstractMatrix,
+        rng::Random.AbstractRNG=Random.default_rng(),
+        classifier::MLJModelInterface.Supervised,
+        samples,
         chain_indices::AbstractVector{Int};
         subset::Real=0.8,
         verbosity::Int=0,
     )
 
-Compute the ``R^*`` convergence statistic of the `samples` with shape (draws, parameters)
-and corresponding chains `chain_indices` with the `classifier`.
+Compute the ``R^*`` convergence statistic of the table `samples` with the `classifier`.
+
+`samples` must be either an `AbstractMatrix`, an `AbstractVector`, or a table
+(i.e. implements the Tables.jl interface) whose rows are draws and whose columns are
+parameters.
+
+`chain_indices` indicates the chain ids of each row of `samples`.
+
+This method supports ragged chains, i.e. chains of nonequal lengths.
+"""
+function rstar(
+    rng::Random.AbstractRNG,
+    classifier::MLJModelInterface.Supervised,
+    x,
+    y::AbstractVector{Int};
+    subset::Real=0.8,
+    verbosity::Int=0,
+)
+    # checks
+    MLJModelInterface.nrows(x) != length(y) && throw(DimensionMismatch())
+    0 < subset < 1 || throw(ArgumentError("`subset` must be a number in (0, 1)"))
+
+    # randomly sub-select training and testing set
+    N = length(y)
+    Ntrain = round(Int, N * subset)
+    0 < Ntrain < N ||
+        throw(ArgumentError("training and test data subsets must not be empty"))
+    ids = Random.randperm(rng, N)
+    train_ids = view(ids, 1:Ntrain)
+    test_ids = view(ids, (Ntrain + 1):N)
+
+    xtable = _astable(x)
+
+    # train classifier on training data
+    ycategorical = MLJModelInterface.categorical(y)
+    xtrain = MLJModelInterface.selectrows(xtable, train_ids)
+    fitresult, _ = MLJModelInterface.fit(
+        classifier, verbosity, xtrain, ycategorical[train_ids]
+    )
+
+    # compute predictions on test data
+    xtest = MLJModelInterface.selectrows(xtable, test_ids)
+    predictions = _predict(classifier, fitresult, xtest)
+
+    # compute statistic
+    ytest = ycategorical[test_ids]
+    result = _rstar(predictions, ytest)
+
+    return result
+end
+
+_astable(x::AbstractVecOrMat) = Tables.table(x)
+_astable(x) = Tables.istable(x) ? x : throw(ArgumentError("Argument is not a valid table"))
+
+# Workaround for https://github.com/JuliaAI/MLJBase.jl/issues/863
+# `MLJModelInterface.predict` sometimes returns predictions and sometimes predictions + additional information
+# TODO: Remove once the upstream issue is fixed
+function _predict(model::MLJModelInterface.Model, fitresult, x)
+    y = MLJModelInterface.predict(model, fitresult, x)
+    return if :predict in MLJModelInterface.reporting_operations(model)
+        first(y)
+    else
+        y
+    end
+end
+
+"""
+    rstar(
+        rng::Random.AbstractRNG=Random.default_rng(),
+        classifier::MLJModelInterface.Supervised,
+        samples::AbstractArray{<:Real,3};
+        subset::Real=0.8,
+        verbosity::Int=0,
+    )
+
+Compute the ``R^*`` convergence statistic of the `samples` with the `classifier`.
+
+`samples` is an array of draws with the shape `(draws, chains, parameters)`.`
 
 This implementation is an adaption of algorithms 1 and 2 described by Lambert and Vehtari.
 
@@ -29,19 +105,17 @@ is returned (algorithm 2).
 
 # Examples
 
-```jldoctest rstar; setup = :(using Random; Random.seed!(100))
+```jldoctest rstar; setup = :(using Random; Random.seed!(101))
 julia> using MLJBase, MLJXGBoostInterface, Statistics
 
-julia> samples = fill(4.0, 300, 2);
-
-julia> chain_indices = repeat(1:3; outer=100);
+julia> samples = fill(4.0, 100, 3, 2);
 ```
 
 One can compute the distribution of the ``R^*`` statistic (algorithm 2) with the
 probabilistic classifier.
 
 ```jldoctest rstar
-julia> distribution = rstar(XGBoostClassifier(), samples, chain_indices);
+julia> distribution = rstar(XGBoostClassifier(), samples);
 
 julia> isapprox(mean(distribution), 1; atol=0.1)
 true
@@ -54,7 +128,7 @@ predicting the mode. In MLJ this corresponds to a pipeline of models.
 ```jldoctest rstar
 julia> xgboost_deterministic = Pipeline(XGBoostClassifier(); operation=predict_mode);
 
-julia> value = rstar(xgboost_deterministic, samples, chain_indices);
+julia> value = rstar(xgboost_deterministic, samples);
 
 julia> isapprox(value, 1; atol=0.2)
 true
@@ -67,60 +141,20 @@ Lambert, B., & Vehtari, A. (2020). ``R^*``: A robust MCMC convergence diagnostic
 function rstar(
     rng::Random.AbstractRNG,
     classifier::MLJModelInterface.Supervised,
-    x::AbstractMatrix,
-    y::AbstractVector{Int};
-    subset::Real=0.8,
-    verbosity::Int=0,
+    x::AbstractArray{<:Any,3};
+    kwargs...,
 )
-    # checks
-    size(x, 1) != length(y) && throw(DimensionMismatch())
-    0 < subset < 1 || throw(ArgumentError("`subset` must be a number in (0, 1)"))
-
-    # randomly sub-select training and testing set
-    N = length(y)
-    Ntrain = round(Int, N * subset)
-    0 < Ntrain < N ||
-        throw(ArgumentError("training and test data subsets must not be empty"))
-    ids = Random.randperm(rng, N)
-    train_ids = view(ids, 1:Ntrain)
-    test_ids = view(ids, (Ntrain + 1):N)
-
-    # train classifier on training data
-    ycategorical = MLJModelInterface.categorical(y)
-    fitresult, _ = MLJModelInterface.fit(
-        classifier, verbosity, Tables.table(x[train_ids, :]), ycategorical[train_ids]
-    )
-
-    # compute predictions on test data
-    xtest = Tables.table(x[test_ids, :])
-    predictions = _predict(classifier, fitresult, xtest)
-
-    # compute statistic
-    ytest = ycategorical[test_ids]
-    result = _rstar(predictions, ytest)
-
-    return result
+    samples = reshape(x, :, size(x, 3))
+    chain_inds = repeat(axes(x, 2); inner=size(x, 1))
+    return rstar(rng, classifier, samples, chain_inds; kwargs...)
 end
 
-# Workaround for https://github.com/JuliaAI/MLJBase.jl/issues/863
-# `MLJModelInterface.predict` sometimes returns predictions and sometimes predictions + additional information
-# TODO: Remove once the upstream issue is fixed
-function _predict(model::MLJModelInterface.Model, fitresult, x)
-    y = MLJModelInterface.predict(model, fitresult, x)
-    return if :predict in MLJModelInterface.reporting_operations(model)
-        first(y)
-    else
-        y
-    end
+function rstar(classif::MLJModelInterface.Supervised, x, y::AbstractVector{Int}; kwargs...)
+    return rstar(Random.default_rng(), classif, x, y; kwargs...)
 end
 
-function rstar(
-    classif::MLJModelInterface.Supervised,
-    x::AbstractMatrix,
-    y::AbstractVector{Int};
-    kwargs...,
-)
-    return rstar(Random.GLOBAL_RNG, classif, x, y; kwargs...)
+function rstar(classif::MLJModelInterface.Supervised, x::AbstractArray{<:Any,3}; kwargs...)
+    return rstar(Random.default_rng(), classif, x; kwargs...)
 end
 
 # R⋆ for deterministic predictions (algorithm 1)
diff --git a/test/Project.toml b/test/Project.toml
index c3a16aaf..09fca5b2 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,10 +1,22 @@
 [deps]
+Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
 FFTW = "7a1cc6ca-52ef-59f5-83cd-3a7055c09341"
+MCMCDiagnosticTools = "be115224-59cd-429b-ad48-344e309966f0"
+MLJBase = "a7f614a8-145f-11e9-1d2a-a57a1082229d"
+MLJLIBSVMInterface = "61c7150f-6c77-4bb1-949c-13197eac2a52"
+MLJXGBoostInterface = "54119dfa-1dab-4055-a167-80440f4f7a91"
 Pkg = "44cfe95a-1eb2-52ea-b672-e2afdf69b78f"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
+Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
+Distributions = "0.25"
 FFTW = "1.1"
-julia = "1"
+MCMCDiagnosticTools = "0.2"
+MLJBase = "0.19, 0.20, 0.21"
+MLJLIBSVMInterface = "0.1, 0.2"
+MLJXGBoostInterface = "0.1, 0.2, 0.3"
+Tables = "1"
+julia = "1.3"
diff --git a/test/discretediag.jl b/test/discretediag.jl
index 8415614f..2796aa96 100644
--- a/test/discretediag.jl
+++ b/test/discretediag.jl
@@ -1,7 +1,8 @@
 @testset "discretediag.jl" begin
     nparams = 4
+    ndraws = 100
     nchains = 2
-    samples = rand(-100:100, 100, nparams, nchains)
+    samples = rand(-100:100, ndraws, nchains, nparams)
 
     @testset "results" begin
         for method in
diff --git a/test/ess.jl b/test/ess.jl
index 4528c735..c58c00b7 100644
--- a/test/ess.jl
+++ b/test/ess.jl
@@ -31,7 +31,7 @@
     end
 
     @testset "ESS and R̂ (IID samples)" begin
-        rawx = randn(10_000, 40, 10)
+        rawx = randn(10_000, 10, 40)
 
         # Repeat tests with different scales
         for scale in (1, 50, 100)
@@ -58,7 +58,7 @@
     end
 
     @testset "ESS and R̂ (identical samples)" begin
-        x = ones(10_000, 40, 10)
+        x = ones(10_000, 10, 40)
 
         ess_standard, rhat_standard = ess_rhat(x)
         ess_standard2, rhat_standard2 = ess_rhat(x; method=ESSMethod())
@@ -75,15 +75,15 @@
     end
 
     @testset "ESS and R̂ (single sample)" begin # check that issue #137 is fixed
-        x = rand(1, 5, 3)
+        x = rand(1, 3, 5)
 
         for method in (ESSMethod(), FFTESSMethod(), BDAESSMethod())
             # analyze array
             ess_array, rhat_array = ess_rhat(x; method=method)
 
-            @test length(ess_array) == size(x, 2)
+            @test length(ess_array) == size(x, 3)
             @test all(ismissing, ess_array) # since min(maxlag, niter - 1) = 0
-            @test length(rhat_array) == size(x, 2)
+            @test length(rhat_array) == size(x, 3)
             @test all(ismissing, rhat_array)
         end
     end
diff --git a/test/gelmandiag.jl b/test/gelmandiag.jl
index 045459e1..23e1a3dd 100644
--- a/test/gelmandiag.jl
+++ b/test/gelmandiag.jl
@@ -1,7 +1,8 @@
 @testset "gelmandiag.jl" begin
     nparams = 4
+    ndraws = 100
     nchains = 2
-    samples = randn(100, nparams, nchains)
+    samples = randn(ndraws, nchains, nparams)
 
     @testset "results" begin
         result = @inferred(gelmandiag(samples))
@@ -23,7 +24,7 @@
     end
 
     @testset "exceptions" begin
-        @test_throws ErrorException gelmandiag(samples[:, :, 1:1])
-        @test_throws ErrorException gelmandiag_multivariate(samples[:, 1:1, :])
+        @test_throws ErrorException gelmandiag(samples[:, 1:1, :])
+        @test_throws ErrorException gelmandiag_multivariate(samples[:, :, 1:1])
     end
 end
diff --git a/test/gewekediag.jl b/test/gewekediag.jl
index f877ccde..5cd8f211 100644
--- a/test/gewekediag.jl
+++ b/test/gewekediag.jl
@@ -3,7 +3,7 @@
 
     @testset "results" begin
         @test @inferred(gewekediag(samples)) isa
-              NamedTuple{(:zscore, :pvalue),Tuple{Float64,Float64}}
+            NamedTuple{(:zscore, :pvalue),Tuple{Float64,Float64}}
     end
 
     @testset "exceptions" begin
diff --git a/test/rstar.jl b/test/rstar.jl
new file mode 100644
index 00000000..928e50a4
--- /dev/null
+++ b/test/rstar.jl
@@ -0,0 +1,112 @@
+using MCMCDiagnosticTools
+
+using Distributions
+using MLJBase
+using MLJLIBSVMInterface
+using MLJXGBoostInterface
+using Tables
+
+using Random
+using Test
+
+const xgboost_deterministic = Pipeline(XGBoostClassifier(); operation=predict_mode)
+
+@testset "rstar.jl" begin
+    classifiers = (XGBoostClassifier(), xgboost_deterministic, SVC())
+    N = 1_000
+
+    @testset "samples input type: $wrapper" for wrapper in [Vector, Array, Tables.table]
+        @testset "examples (classifier = $classifier)" for classifier in classifiers
+            sz = wrapper === Vector ? N : (N, 2)
+            # Compute R⋆ statistic for a mixed chain.
+            samples = wrapper(randn(sz...))
+            dist = rstar(classifier, samples, rand(1:3, N))
+
+            # Mean of the statistic should be focused around 1, i.e., the classifier does not
+            # perform better than random guessing.
+            if classifier isa MLJBase.Deterministic
+                @test dist isa Float64
+            else
+                @test dist isa LocationScale
+                @test dist.ρ isa PoissonBinomial
+                @test minimum(dist) == 0
+                @test maximum(dist) == 3
+            end
+            @test mean(dist) ≈ 1 rtol = 0.2
+            wrapper === Vector && break
+
+            # Compute R⋆ statistic for a mixed chain.
+            samples = wrapper(randn(4 * N, 8))
+            chain_indices = repeat(1:4, N)
+            dist = rstar(classifier, samples, chain_indices)
+
+            # Mean of the statistic should be closte to 1, i.e., the classifier does not perform
+            # better than random guessing.
+            if classifier isa MLJBase.Deterministic
+                @test dist isa Float64
+            else
+                @test dist isa LocationScale
+                @test dist.ρ isa PoissonBinomial
+                @test minimum(dist) == 0
+                @test maximum(dist) == 4
+            end
+            @test mean(dist) ≈ 1 rtol = 0.15
+
+            # Compute the R⋆ statistic for a non-mixed chain.
+            samples = wrapper([
+                sin.(1:N) cos.(1:N)
+                100 .* cos.(1:N) 100 .* sin.(1:N)
+            ])
+            chain_indices = repeat(1:2; inner=N)
+            dist = rstar(classifier, samples, chain_indices)
+
+            # Mean of the statistic should be close to 2, i.e., the classifier should be able to
+            # learn an almost perfect decision boundary between chains.
+            if classifier isa MLJBase.Deterministic
+                @test dist isa Float64
+            else
+                @test dist isa LocationScale
+                @test dist.ρ isa PoissonBinomial
+                @test minimum(dist) == 0
+                @test maximum(dist) == 2
+            end
+            @test mean(dist) ≈ 2 rtol = 0.15
+        end
+        wrapper === Vector && continue
+
+        @testset "exceptions (classifier = $classifier)" for classifier in classifiers
+            samples = wrapper(randn(N - 1, 2))
+            @test_throws DimensionMismatch rstar(classifier, samples, rand(1:3, N))
+            for subset in (-0.3, 0, 1 / (3 * N), 1 - 1 / (3 * N), 1, 1.9)
+                samples = wrapper(randn(N, 2))
+                @test_throws ArgumentError rstar(
+                    classifier, samples, rand(1:3, N); subset=subset
+                )
+            end
+        end
+    end
+
+    @testset "table with chain_ids produces same result as 3d array" begin
+        nparams = 2
+        nchains = 3
+        samples = randn(N, nchains, nparams)
+
+        # manually construct samples_mat and chain_inds for comparison
+        samples_mat = reshape(samples, N * nchains, nparams)
+        chain_inds = Vector{Int}(undef, N * nchains)
+        i = 1
+        for chain in 1:nchains, draw in 1:N
+            chain_inds[i] = chain
+            i += 1
+        end
+
+        @testset "classifier = $classifier" for classifier in classifiers
+            rng = MersenneTwister(42)
+            dist1 = rstar(rng, classifier, samples_mat, chain_inds)
+            Random.seed!(rng, 42)
+            dist2 = rstar(rng, classifier, samples)
+            @test dist1 == dist2
+            @test typeof(rstar(classifier, samples)) === typeof(dist2)
+        end
+    end
+end
diff --git a/test/rstar/Project.toml b/test/rstar/Project.toml
deleted file mode 100644
index 91673a0c..00000000
--- a/test/rstar/Project.toml
+++ /dev/null
@@ -1,15 +0,0 @@
-[deps]
-Distributions = "31c24e10-a181-5473-b8eb-7969acd0382f"
-MCMCDiagnosticTools = "be115224-59cd-429b-ad48-344e309966f0"
-MLJBase = "a7f614a8-145f-11e9-1d2a-a57a1082229d"
-MLJLIBSVMInterface = "61c7150f-6c77-4bb1-949c-13197eac2a52"
-MLJXGBoostInterface = "54119dfa-1dab-4055-a167-80440f4f7a91"
-Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
-
-[compat]
-Distributions = "0.25"
-MCMCDiagnosticTools = "0.1"
-MLJBase = "0.19, 0.20, 0.21"
-MLJLIBSVMInterface = "0.1, 0.2"
-MLJXGBoostInterface = "0.1, 0.2, 0.3"
-julia = "1.3"
diff --git a/test/rstar/runtests.jl b/test/rstar/runtests.jl
deleted file mode 100644
index 00869743..00000000
--- a/test/rstar/runtests.jl
+++ /dev/null
@@ -1,79 +0,0 @@
-using MCMCDiagnosticTools
-
-using Distributions
-using MLJBase
-using MLJLIBSVMInterface
-using MLJXGBoostInterface
-
-using Test
-
-const xgboost_deterministic = Pipeline(XGBoostClassifier(); operation=predict_mode)
-
-@testset "rstar.jl" begin
-    classifiers = (XGBoostClassifier(), xgboost_deterministic, SVC())
-    N = 1_000
-
-    @testset "examples (classifier = $classifier)" for classifier in classifiers
-        # Compute R⋆ statistic for a mixed chain.
-        samples = randn(N, 2)
-        dist = rstar(classifier, randn(N, 2), rand(1:3, N))
-
-        # Mean of the statistic should be focused around 1, i.e., the classifier does not
-        # perform better than random guessing.
-        if classifier isa MLJBase.Deterministic
-            @test dist isa Float64
-        else
-            @test dist isa LocationScale
-            @test dist.ρ isa PoissonBinomial
-            @test minimum(dist) == 0
-            @test maximum(dist) == 3
-        end
-        @test mean(dist) ≈ 1 rtol = 0.2
-
-        # Compute R⋆ statistic for a mixed chain.
-        samples = randn(4 * N, 8)
-        chain_indices = repeat(1:4, N)
-        dist = rstar(classifier, samples, chain_indices)
-
-        # Mean of the statistic should be closte to 1, i.e., the classifier does not perform
-        # better than random guessing.
-        if classifier isa MLJBase.Deterministic
-            @test dist isa Float64
-        else
-            @test dist isa LocationScale
-            @test dist.ρ isa PoissonBinomial
-            @test minimum(dist) == 0
-            @test maximum(dist) == 4
-        end
-        @test mean(dist) ≈ 1 rtol = 0.15
-
-        # Compute the R⋆ statistic for a non-mixed chain.
-        samples = [
-            sin.(1:N) cos.(1:N)
-            100 .* cos.(1:N) 100 .* sin.(1:N)
-        ]
-        chain_indices = repeat(1:2; inner=N)
-        dist = rstar(classifier, samples, chain_indices)
-
-        # Mean of the statistic should be close to 2, i.e., the classifier should be able to
-        # learn an almost perfect decision boundary between chains.
-        if classifier isa MLJBase.Deterministic
-            @test dist isa Float64
-        else
-            @test dist isa LocationScale
-            @test dist.ρ isa PoissonBinomial
-            @test minimum(dist) == 0
-            @test maximum(dist) == 2
-        end
-        @test mean(dist) ≈ 2 rtol = 0.15
-    end
-
-    @testset "exceptions (classifier = $classifier)" for classifier in classifiers
-        @test_throws DimensionMismatch rstar(classifier, randn(N - 1, 2), rand(1:3, N))
-        for subset in (-0.3, 0, 1 / (3 * N), 1 - 1 / (3 * N), 1, 1.9)
-            @test_throws ArgumentError rstar(
-                classifier, randn(N, 2), rand(1:3, N); subset=subset
-            )
-        end
-    end
-end
diff --git a/test/runtests.jl b/test/runtests.jl
index 54c058a6..63fdade0 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1,12 +1,5 @@
 using Pkg
 
-# Activate test environment on older Julia versions
-@static if VERSION < v"1.2"
-    Pkg.activate(@__DIR__)
-    Pkg.develop(PackageSpec(; path=dirname(@__DIR__)))
-    Pkg.instantiate()
-end
-
 using MCMCDiagnosticTools
 using FFTW
 
@@ -43,16 +36,11 @@ Random.seed!(1)
         include("rafterydiag.jl")
     end
     @testset "R⋆ diagnostic" begin
-        # MLJXGBoostInterface requires Julia >= 1.3
         # XGBoost errors on 32bit systems: https://github.com/dmlc/XGBoost.jl/issues/92
-        if VERSION >= v"1.3" && Sys.WORD_SIZE == 64
-            # run tests related to rstar statistic
-            Pkg.activate("rstar")
-            Pkg.develop(; path=dirname(dirname(pathof(MCMCDiagnosticTools))))
-            Pkg.instantiate()
-            include(joinpath("rstar", "runtests.jl"))
+        if Sys.WORD_SIZE == 64
+            include("rstar.jl")
         else
-            @info "R⋆ not tested: requires Julia >= 1.3 and a 64bit architecture"
+            @info "R⋆ not tested: requires 64bit architecture"
         end
     end
 end