diff --git a/03-documentation/terms_of_reference-key_terms.md b/03-documentation/terms_of_reference-key_terms.md
index 49a4e52..7d7e5ac 100644
--- a/03-documentation/terms_of_reference-key_terms.md
+++ b/03-documentation/terms_of_reference-key_terms.md
@@ -175,3 +175,13 @@ forms of inequality:
         - unemployment: forecloses income prospects; highest rate in young people
         - underemployment: low wages make meeting basic needs impossible (esp. food, healthcare, education, decent housing)
             - split into time-related underemployment and potential labour force
+
+# Additional Terms
+
+## Methods
+
+### Survey-based
+
+- Likert scale (1-4/1-5 scale questionnaire)
+- Cronbach's alpha test score (reports coherence of set of items in a group)
+- Binary answer (yes/no)