This method is very simple and easy to understand. It is applicable for linear and non-linear trends. It gives us a idea about the rise and fall of the time series. For every long time series, the graph of the original data enables us to decide about the application of more mathematical models for the measurement of trend. A monthly data of 5 years has 60 values. A graph of these values may suggest that the trend is linear for the first two years (24 values) and for the next 3 years, it is non-linear. We accordingly apply the linear approach on the first 24 values and the curvilinear techniques on the next 36 values.
It is not mathematical in nature. Different persons may draw a different trend. The method does not appeal to a common man because it seems as if it is something rough and crude.