diff --git a/Manifest.toml b/Manifest.toml
index 650cad8b..e8c5a6c3 100644
--- a/Manifest.toml
+++ b/Manifest.toml
@@ -35,9 +35,9 @@ version = "1.0.6+5"
 
 [[ChainRulesCore]]
 deps = ["Compat", "LinearAlgebra", "SparseArrays"]
-git-tree-sha1 = "0893f8d90331a0f5223c7ef2a8868464394a886c"
+git-tree-sha1 = "44e9f638aa9ed1ad58885defc568c133010140aa"
 uuid = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
-version = "0.9.33"
+version = "0.9.37"
 
 [[CodecBzip2]]
 deps = ["Bzip2_jll", "Libdl", "TranscodingStreams"]
@@ -53,9 +53,9 @@ version = "0.7.0"
 
 [[Compat]]
 deps = ["Base64", "Dates", "DelimitedFiles", "Distributed", "InteractiveUtils", "LibGit2", "Libdl", "LinearAlgebra", "Markdown", "Mmap", "Pkg", "Printf", "REPL", "Random", "SHA", "Serialization", "SharedArrays", "Sockets", "SparseArrays", "Statistics", "Test", "UUIDs", "Unicode"]
-git-tree-sha1 = "919c7f3151e79ff196add81d7f4e45d91bbf420b"
+git-tree-sha1 = "4fecfd5485d3c5de4003e19f00c6898cccd40667"
 uuid = "34da2185-b29b-5c13-b0c7-acf172513d20"
-version = "3.25.0"
+version = "3.26.0"
 
 [[CompilerSupportLibraries_jll]]
 deps = ["Artifacts", "Libdl"]
@@ -288,15 +288,15 @@ version = "1.1.3"
 
 [[Rmath]]
 deps = ["Random", "Rmath_jll"]
-git-tree-sha1 = "86c5647b565873641538d8f812c04e4c9dbeb370"
+git-tree-sha1 = "bf3188feca147ce108c76ad82c2792c57abe7b1f"
 uuid = "79098fc4-a85e-5d69-aa6a-4863f24498fa"
-version = "0.6.1"
+version = "0.7.0"
 
 [[Rmath_jll]]
 deps = ["Artifacts", "JLLWrappers", "Libdl", "Pkg"]
-git-tree-sha1 = "1b7bf41258f6c5c9c31df8c1ba34c1fc88674957"
+git-tree-sha1 = "68db32dff12bb6127bac73c209881191bf0efbb7"
 uuid = "f50d1b31-88e8-58de-be2c-1cc44531875f"
-version = "0.2.2+2"
+version = "0.3.0+0"
 
 [[SHA]]
 uuid = "ea8e919c-243c-51af-8825-aaa63cd721ce"
@@ -329,9 +329,9 @@ version = "1.3.0"
 
 [[StaticArrays]]
 deps = ["LinearAlgebra", "Random", "Statistics"]
-git-tree-sha1 = "9da72ed50e94dbff92036da395275ed114e04d49"
+git-tree-sha1 = "2f01a51c23eed210ff4a1be102c4cc8236b66e5b"
 uuid = "90137ffa-7385-5640-81b9-e52037218182"
-version = "1.0.1"
+version = "1.1.0"
 
 [[Statistics]]
 deps = ["LinearAlgebra", "SparseArrays"]
@@ -345,9 +345,9 @@ version = "0.33.4"
 
 [[StatsFuns]]
 deps = ["Rmath", "SpecialFunctions"]
-git-tree-sha1 = "3b9f665c70712af3264b61c27a7e1d62055dafd1"
+git-tree-sha1 = "ced55fd4bae008a8ea12508314e725df61f0ba45"
 uuid = "4c63d2b9-4356-54db-8cca-17b64c39e42c"
-version = "0.9.6"
+version = "0.9.7"
 
 [[SuiteSparse]]
 deps = ["Libdl", "LinearAlgebra", "Serialization", "SparseArrays"]
diff --git a/Project.toml b/Project.toml
index 3277931b..faab70f8 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "Psychometrics"
 uuid = "ce8202d9-98c3-4990-890a-8616ce2c06f9"
 authors = ["Giada Spaccapanico Proietti"]
-version = "0.4.4"
+version = "0.4.5"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"
diff --git a/src/information/item_expected_information.jl b/src/information/item_expected_information.jl
index 1700a460..a794f1ee 100644
--- a/src/information/item_expected_information.jl
+++ b/src/information/item_expected_information.jl
@@ -23,7 +23,7 @@ A `Float64` scalar.
 """
 function _item_expected_information(parameters::Parameters1PL, latent::Latent1D)
     p = _probability(latent, parameters)
-    return (latent.val - parameters.b)^2 * p * (1 - p)::Float64
+    return p * (1 - p)::Float64
 end
 
 ########################################################################
diff --git a/src/information/item_observed_information.jl b/src/information/item_observed_information.jl
index 7fe16fcc..b61769c8 100644
--- a/src/information/item_observed_information.jl
+++ b/src/information/item_observed_information.jl
@@ -28,10 +28,7 @@ function _item_observed_information(
     latent::Latent1D,
     response_val::Float64
 )
-    p = _probability(latent, parameters)
-    i_bb = - (- p^2) * (1 - p) * p / (p^2) # v p.49 Kim, Baker: - L_22
-    return i_bb::Float64
-   # return _item_expected_information(parameters, latent)::Matrix{Float64}
+    return _item_expected_information(parameters, latent)::Float64
 end
 
 ########################################################################
@@ -68,15 +65,14 @@ function _item_observed_information(
 )
     #return _item_expected_information(parameters, latent)::Matrix{Float64}
     p = _probability(latent, parameters)
-    h = (- p^2) * (1 - p) * p
-    den = p^2
-    i_aa = - h * (latent.val - parameters.b)^2 / den # v p.49 Kim, Baker: - L_11
+    p_1_p = p * (1 - p)
+    i_aa = p_1_p * (latent.val - parameters.b)^2 # v p.49 Kim, Baker: - L_11
     i_ab =
         (
-            p * ((parameters.a * (latent.val - parameters.b) * h) +
-            (p * (response_val - p)))
-        ) / den # X p.50 Kim, Baker: - L_12 #TODO
-    i_bb = - parameters.a^2 * h / den # v p.49 Kim, Baker: - L_22
+             ((parameters.a * (latent.val - parameters.b) * (- p) * p_1_p) +
+             (response_val - p))
+        )  # X p.50 Kim, Baker: - L_12 #TODO
+    i_bb = - parameters.a^2 * p_1_p # v p.49 Kim, Baker: - L_22
     return [i_aa i_ab; i_ab i_bb]::Matrix{Float64}
 end