Returns the average fractional growth rate (negative for decline) in the input. Equivalent to the equations:
TREND=ZIDZ(input-avval,average time*ABS(avval))
avval=INTEG((input-avval)/average time,input/(1+ini*averate time))
The TREND function provides a very simple trend estimate for a variable. It really only makes sense for numbers that are always positive and don’t get very close to zero. If you want to trend a number that may be positive or negative the TREND function is not very useful. Instead, you should use the fractional trend relative to a quantity that is always positive (for example change in profit as a fraction of gross income).
Units: TREND(units,time,1/time) --> 1/time
Units for the average time must match those of TIME STEP.
Example
R = 10 + RAMP(1,30,70)
TR = TREND(R,5,.08)
Sample model: TREND.mdl in FunctionExamples
