diff --git a/ALGORITHM.md b/ALGORITHM.md
index 0bcf46b..a6d3d51 100644
--- a/ALGORITHM.md
+++ b/ALGORITHM.md
@@ -15,3 +15,5 @@ One of the following contexts is used:
 - last two bytes
 - last byte
 - no context (encode directly the index into the dictionary)
+
+The decision on which context to use is based on an estimate of the compression using unary and Golom-Rice coding.