How to label a constant y-axis in a grid of plots? I have a grid of plots (see example below) with different x axes but all the same y-axis. What is the best way to label the y-axis without being redundant? The information is in the legend, but this is not a solution.
Here are two options I am considering:


*

*center one label on the right hand side in the same font as the x-axis labels. This could make it ambiguous if the y-axis label is associated with only one subplot.

*leave the y-axis empty and provide information in a figure title (response of 'y-axis label (units)' to 15 variables).


This plot will be published in a scientific journal. Low resolution is intentional for this post since it is unpubliished. Any other suggestions appreciated.

 A: I don't know what the perfect solution is here. I might ask others in the same field, or who have experience with that journal what has worked for them or what they suggest.  My initial thought would be to label y-axes on the left hand side of the plots that are in the leftmost column.  Then I might decrease the vertical margins between the plots relative to the horizontal margins between the plots.  The gestalt will make the rows salient and visually highlight that they all share the same y-axis labels on the left.  (You'd have to see how this looks, but I think it might work.)  Furthermore, I would group the plots with the same x-axes by column if possible (even though I gather you're still going to have x-axes for every plot), and definitely point these facts out in the figure caption.  
I should say, at this point, that I can't read your figure, I wonder if you could make and submit a high-resolution version and let the typesetting people reduce the resolution or figure out what they want to do with it.  For example, sometimes they can keep a higher-resolution version at the journal's website or something.  
