As for frequency or severity trend, Simulator implements a “month-of-month” (monthly frequency or monthly severity trend). The model calculates the “cumulative trend” as follows, using j as the month index:
Cumul Trend (j) = Cumul Trend (j-1) * Trend Input (j)
Under this interpretation, a factor of 1.01 would mean a effective trend of 1% monthly. To obtain a 10% effective annual trend, one would enter the amount 1.01^(1/12) for the monthly trend factor.