[Gretl-users] (NBER) recession shading in gretl/gnuplot

Hi, here's a little detail thingy about the built-in NBER recession shading. It's not really a bug (I think), but perhaps a little bit misleading. Gretl uses the dates of the NBER peaks and troughs (I'm talking about monthly data now) to determine the beginning and end of the shading. For example, one NBER peak is 2001M3 (March), and so gretl's shading starts immediately after February, covering all of the March interval in the plot. Therefore, the observed March value of any plotted variable is a bit "later" (= to the right), because the point is centered within the March interval. So the peak value will always be "inside" the recession. It seems that that's not the conventional way of presenting the recessions. If you look at a time series plot on the FRED webpage for example, the March value will be shown right at the beginning of the shading. Also, FRED offers an indicator series for the NBER recessions which explicitly says "starting with the period after the peak". It's a matter of convention, but I think the FRED shading makes more sense than the current gretl shading. So: I suggest that either the shading should start in the middle of the period (middle of March in this example). But given that that may not be feasible with gnuplot, I would suggest to adopt the FRED convention and start the shading right after the peak dates. thanks, sven