Advanced Data Analytics Using Python_ With Machine Learning, Deep Learning and NLP Examples ( 2023)

Chapter 6
Time Series
Figure 6-1. A time series with trends
The simplest type of time series is the familiar “linear trend plus noise”
for which the observation at time t is a random variable X t , as follows:
X t
= a + bt
+ e
Here, α,β are constants, and ε t denotes a random error term with
a mean of 0. The average level at time t is given by m t = (α + βt). This is
sometimes called the trend term.
t
Curve Fitting
Fitting a simple function of time such as a polynomial curve (linear,
quadratic, etc.), a Gompertz curve, or a logistic curve is a well-known
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