diff --git a/src/additional_functions/helper.jl b/src/additional_functions/helper.jl
index 26d079b00..91095e071 100644
--- a/src/additional_functions/helper.jl
+++ b/src/additional_functions/helper.jl
@@ -114,11 +114,11 @@ function sparse_outer_mul!(C, A, B::Vector, ind) #computes A*S*B -> C, where ind
 end
 
 function cov_and_mean(rows; corrected = false)
-    data = permutedims(hcat(rows...))
+    data = transpose(reduce(hcat, rows))
     size(rows, 1) > 1 ?
         obs_cov = Statistics.cov(data; corrected = corrected) :
         obs_cov = reshape([0.0],1,1)
-    obs_mean = vcat(Statistics.mean(data, dims = 1)...)
+    obs_mean = vec(Statistics.mean(data, dims = 1))
     return obs_cov, obs_mean
 end
 
diff --git a/src/additional_functions/parameters.jl b/src/additional_functions/parameters.jl
index b381e1c32..13aa1cd41 100644
--- a/src/additional_functions/parameters.jl
+++ b/src/additional_functions/parameters.jl
@@ -103,7 +103,7 @@ function get_matrix_derivative(M_indices, parameters, n_long)
         ones(length(M_indices[i])),
         n_long) for i in 1:length(parameters)]
 
-    ∇M = hcat(∇M...)
+    ∇M = reduce(hcat, ∇M)
 
     return ∇M
 
diff --git a/test/examples/multigroup/multigroup.jl b/test/examples/multigroup/multigroup.jl
index a86371caa..5ef6bd8c6 100644
--- a/test/examples/multigroup/multigroup.jl
+++ b/test/examples/multigroup/multigroup.jl
@@ -21,25 +21,24 @@ dat_miss_g2 = dat_missing[dat_missing.school .== "Grant-White", :]
 ############################################################################################
 
 x = Symbol.(:x, 1:36)
-#x = [x...]
 
 F = zeros(9, 12)
 F[diagind(F)] .= 1.0
 
 A = Matrix{Any}(zeros(12, 12))
 A[1, 10] = 1.0; A[4, 11] = 1.0; A[7, 12] = 1.0
-A[2:3, 10] .= [x...][16:17]; A[5:6, 11] .= [x...][18:19]; A[8:9, 12] .= [x...][20:21]; 
+A[2:3, 10] .= x[16:17]; A[5:6, 11] .= x[18:19]; A[8:9, 12] .= x[20:21];
 
 # group 1
 S1 = Matrix{Any}(zeros(12, 12))
-S1[diagind(S1)] .= [x...][1:12]
+S1[diagind(S1)] .= x[1:12]
 S1[10, 11] = x[13]; S1[11, 10] = x[13]
 S1[10, 12] = x[14]; S1[12, 10] = x[14]
 S1[12, 11] = x[15]; S1[11, 12] = x[15]
 
 # group 2
 S2 = Matrix{Any}(zeros(12, 12))
-S2[diagind(S2)] .= [x...][22:33]
+S2[diagind(S2)] .= x[22:33]
 S2[10, 11] = x[34]; S2[11, 10] = x[34]
 S2[10, 12] = x[35]; S2[12, 10] = x[35]
 S2[12, 11] = x[36]; S2[11, 12] = x[36]