diff --git a/automata/period_automaton.jl b/automata/period_automaton.jl
index b5632614a6fbb5b2e4cc01999d550868e585f963..3c62d794d949027989a882e14f51adcdd3898efd 100644
--- a/automata/period_automaton.jl
+++ b/automata/period_automaton.jl
@@ -8,6 +8,9 @@
 @everywhere mean_error(mean_tp::Float64, var_tp::Float64, ref_mean_tp::Float64, ref_var_tp::Float64) =
 abs(mean_tp - ref_mean_tp)
 
+@everywhere min_mean_var_relative_error(mean_tp::Float64, var_tp::Float64, ref_mean_tp::Float64, ref_var_tp::Float64) =
+min(abs((mean_tp - ref_mean_tp)/ref_mean_tp), sqrt(var_tp)/ref_mean_tp)
+
 # Creation of the automaton types
 #@everywhere @eval abstract type EdgePeriodAutomaton <: Edge end
 @everywhere struct EdgePeriodAutomaton <: Edge