From d058f524b7dd36bc5d4d382d03762a6cad2207a4 Mon Sep 17 00:00:00 2001
From: Milan Bouchet-Valat <nalimilan@club.fr>
Date: Thu, 2 Jun 2022 18:45:32 +0200
Subject: [PATCH] Adjust definition of null model when there is no intercept
 (#14)
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Technically this is breaking, but the current definition gives negative R² for models without the intercept.
---
 Project.toml            |  2 +-
 src/statisticalmodel.jl | 13 ++++++++++---
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/Project.toml b/Project.toml
index cb9e608..555f422 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "StatsAPI"
 uuid = "82ae8749-77ed-4fe6-ae5f-f523153014b0"
 authors = ["Milan Bouchet-Valat <nalimilan@club.fr"]
-version = "1.3.0"
+version = "1.4.0"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
diff --git a/src/statisticalmodel.jl b/src/statisticalmodel.jl
index d0f6d2c..e8f4f68 100644
--- a/src/statisticalmodel.jl
+++ b/src/statisticalmodel.jl
@@ -57,7 +57,11 @@ function islinear end
 """
     nulldeviance(model::StatisticalModel)
 
-Return the deviance of the null model, that is the one including only the intercept.
+Return the deviance of the null model, obtained by dropping all
+independent variables present in `model`.
+
+If `model` includes an intercept, the null model is the one with only the intercept;
+otherwise, it is the one without any predictor (not even the intercept).
 """
 function nulldeviance end
 
@@ -81,8 +85,11 @@ function loglikelihood end
 """
     nullloglikelihood(model::StatisticalModel)
 
-Return the log-likelihood of the null model corresponding to `model`.
-This is usually the model containing only the intercept.
+Return the log-likelihood of the null model, obtained by dropping all
+independent variables present in `model`.
+
+If `model` includes an intercept, the null model is the one with only the intercept;
+otherwise, it is the one without any predictor (not even the intercept).
 """
 function nullloglikelihood end