With apologies for having distracted Eduardo's thread on abortion, I decided to make this a separate thread.  David Gibson wrote that "data" as a singular noun is acceptable in certain contexts, at  least according to Merriam-Webster online.  For me "this data" has the same effect as fingernails screeching down a blackboard.  But I'm old...

So I checked Merriam-Webster for two analogous cases, and here is what it said, first, about "memorandum/memoranda":

"Although some commentators warn against the use of memoranda as a singular and condemn the plural memorandas, our evidence indicates that these forms are rarely encountered in print. We have a little evidence of the confusion of forms, including use of memorandum as a plural, in speech (as at congressional hearings). As plurals memoranda and memorandums are about equally frequent."

and then  about "criterion/criteria":

"The plural criteria has been used as a singular for over half a century <let me now return to the third criteria R. M. Nixon> <that really is the criteria Bert Lance>. Many of our examples, like the two foregoing, are taken from speech. But singular criteria is not uncommon in edited prose, and its use both in speech and writing seems to be increasing. Only time will tell whether it will reach the unquestioned acceptability of agenda."

(It's too bad they didn't give an  example from Richard Nixon for "this data"; that would have held the abomination back for a few more decades!)

Fair warning to all, however.  That the past tense of the verb "lead" is "led" is fast disappearing from American consciousness, at least to judge from students' papers.

Does "Commonweal" have a usage-guide?  .