In this blog post graphic methods are used to describe Serbian monthly catering time series.
Two types of a line graph could be used to show changes in monthly catering over time. The first displays both time series on a single graph. The second type of graph displays each series on a separate panel. On such graphs any persistent pattern related to trend or seasonal factors should be clearly visible.
Figure 1 shows line graphs of monthly catering time series on the same panel.
As we expected catering series in current prices shows persistent upward trend with a little break during 2008. However, catering series in constant prices varies around a constant level until 2008, then dropped to lower level and started to increase after 2013.
Figure 2 shows line graphs of monthly catering time series on the separate panels.
On the graphs in Figure 2 the differences in seasonal patterns between catering series in constant and current prices are not quite clearly visible. However, we may spot the changes in seasonal patterns in these two series before and after 2013. On the graphs in Figure 1 two series show similar seasonal patterns after 2013. The seasonal patterns and differences between two series will be further examined on the seasonal plots.