
Chapter 16
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important. Without the knowledge of these seasonal uctuations, the sales manager may commit
mistakes in judging seasonal upswings and seasonal slumps that may affect demand. Therefore,
for understanding the behaviour of the phenomenon in a time series, the data must be adjusted
for seasonal variations. This technique is called de-personalization and will be discussed later in
this chapter.
16.5.3 Cyclical Variations
Cyclical variations refer to oscillatory movements in a time series with a period of oscillation
of more than a year. Cyclical variations are the components of a time series that tend to oscillate
above and below the ...