The two typos you mentioned are of the same type - incorrect column headers on main tables. The potential for that error mainly comes from us building about 60 all new MRS tables this year, not to mention the dozens of new side charts.
I do a lot of the work with the tables and charts and am also the one who proofreads them. If you've ever tried to proofread your own stuff you know it's easy to miss things.
So, while several people look over every page of the issue before it goes to print, I will have someone in addition to myself specifically look at the tables and charts, especially the headings. The fact that we have egg on our face twice over on the same type of error will make that issue stick in our heads pretty well, if you know what I mean.
See? - Your feedback does help us improve the magazines. Thanks.