Quotes Uncovered: What's the Plural of Anecdote?

Photo: D Sharon Pruitt

Each week, I’ve been inviting readers to submit quotations whose origins they want me to try to trace, using my book, The Yale Book of Quotations, and my more recent research. Here is the latest round.
Eric asked:

“The plural of anecdote is not data.” I love this line as it appeals to my inner economist. Any idea who said it first?

This is a fascinating quotation, in that it gets 213,000 hits on Google, whereas its opposite, “The plural of anecdote is data,” gets only 9,000 hits. Yet “The plural of anecdote is data” is the original saying, and the logical one (what is data if not the accumulation of anecdotes?).
The earliest version I find is an article in the political science journal, PS, Autumn 1984, in which Nelson W. Polsby referred to “Raymond Wolfinger‘s brilliant aphorism ‘the plural of anecdote is data.'”
I e-mailed Wolfinger a few years ago and got the following response from him:

I said ‘The plural of anecdote is data” some time in the 1969-70 academic year while teaching a graduate seminar at Stanford. The occasion was a student’s dismissal of a simple factual statement — by another student or me — as a mere anecdote. The quotation was my rejoinder.

I also e-mailed Polsby, who didn’t know of any early printed occurrences.
David asked:

I have long thought Mark Twain was responsible for “Nothing needs reform like other people’s behavior,” but it is not included in common collections of his famous quotes. Would love to know it’s origin, as it is so useful these days.

This is a rare example of a quote attributed to Mark Twain that really was by Mark Twain. The Yale Book of Quotations has it as follows:

“Nothing so needs reforming as other people’s habits.”
Mark Twain, Pudd’nhead Wilson (1894)

matt asked:

I’ve always been curious about… “take it with a grain of salt” how did this evolve into advice to be dubious?

The Yale Book of Quotations says:

Addito salis grano.
With the addition of a grain of salt.
Pliny the Elder, Historia Naturalis, bk. 23, sec. 149. Usually quoted as “Cum grano salis” (with a grain of salt). The reference is to salt being added to Pompey’s antidote to poison.

Do any readers have any other quotations whose origins they would like me to attempt to trace?