Add clarification about time units
@@ -212,6 +212,10 @@ def sabelhaus_song_var_profile(age_min=27, age_max=54, cohort=None,
Note that TransShkStd[n] and PermShkStd[n] are the volatilities of
shocks _experienced_ at age Age[n], (not those expected at Age[n+1]
from the perspective of Age[n]).
+
+ Note that Sabelhaus and Song work in discrete time and with periods
+ that represent one year. Therefore, the outputs must be interpreted
+ at the yearly frequency.
"""
assert age_max >= age_min, (
