Centering the header of individual graphs in SPGRAPH

[PTillmann-436]

I am using SPGRAPH to create a matrix of graphs. The larger I make the horizontal dimension (hfield=4,vfield=1 in my example), the less the headers of the individual graphs appear centered. Please see the figure attached. How can I solve that? Many thanks in advance.

[TomDoan]

The labels that are outside the box are centered within the "page", not over the graph box---the size of the graph box is determined after the various labels are placed. Because your vertical axis labels are much larger than typical relative to the graph, it makes centered on the page look skewed compared with centered on the graph box.