Seasonal subseries plot  From Wikipedia, the free encyclopedia
Jump to: navigation, search  Seasonal subseries plots are a tool
for detecting seasonality in a time series. This plot allows one
to detect both between-group and within-group patterns. 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. If the period is not
known, an autocorrelation plot or spectral plot can be used to
determine it. If there is a large number of observations, then a
box plot may be preferable.   Seasonal subseries plots are
formed by    • Vertical axis: response variable   • Horizontal
axis: time ordered by season. For example, with monthly data,
all the January values are plotted (in chronological order),
then all the February values, and so on.  In addition, a
reference line is drawn at the group means.  The analyst must
specify the length of the seasonal pattern before generating
this plot. In most cases,