Final answer:
Frequency is not used to describe the timeframe of a trend. Duration, period, and magnitude are used.
Step-by-step explanation:
In the given options, all except Frequency are used to describe the timeframe of a trend.
Duration refers to the length of time that a trend continues.
Period refers to the time it takes to complete one cycle of a trend.
Magnitude refers to the size or scale of a trend, which can be measured quantitatively.
On the other hand, Frequency describes how often a trend occurs in a given period of time.