Process or Product Monitoring and Control 6.4. Introduction to
Time Series Analysis 6.4.4. Univariate Time Series Models
Seasonal subseries plots 1993) are a tool for detecting
seasonality in a time series. This plot is only useful if the
period of the seasonality is already known. In many cases, this
will in fact be known. For example, monthly data typically has a
period of 12. This seasonal subseries plot containing monthly
data of CO2 concentrations reveals a strong seasonality pattern.
The CO2 concentrations peak in May, steadily decrease through
September, and then begin rising again until the May peak. This
plot allows you to detect both between group and within group
patterns. If there is a large number of observations, then a box
plot may be preferable. Seasonal subseries plots are formed by
The user must specify the length of the seasonal pattern before
generating this plot. In most cases, the analyst will know this
from the context of the problem and data collection. Sometimes
the series will need t