time series analysis
An arithmetic trending technique that assumes that the variable to be forecast
(known as the dependent variable) varies predictably with time (the independent
variable). This type of analysis is comparable to regression analysis; however,
time series analysis assumes that the dependent variable (such as the annual
number of losses) varies only with the passage of time. Given any future time
period, the trend line can be extended to develop estimates of loss frequency
and loss severity for various kinds of exposures.