“Your guess is as good as mine” is an old saying meaning that neither person knows for certain about something. An economist “guesses” about the economy, but it’s supposed to be an educated guess that’s more informed than anyone else’s. Economic predictions have long been a subject of humor.
 
“I would never make an economist in the world,” said humorist Will Rogers (1879-1935) in a radio broadcast on May 26, 1935. “An economist is a man that can tell you anything about — he’ll tell you what can happen under any given conditions, and his guess is liable to be just as good as anybody else’s, too.”
 
Rogers’ saying is often simplified to: “An economist’s guess is liable to be as good as anybody else’s.”
 
   
Wikipedia: Will Rogers
William Penn Adair Rogers (better known as “Will” Rogers) (November 4, 1879 – August 15, 1935) was an American cowboy, comedian, humorist, social commentator, vaudeville performer and actor and one of the best-known celebrities in the 1920s and 1930s.
 
Known as Oklahoma’s favorite son, Rogers was born to a prominent Cherokee Nation family in Indian Territory (now part of Oklahoma). He traveled around the world three times, made 71 movies (50 silent films and 21 “talkies”), wrote more than 4,000 nationally-syndicated newspaper columns, and became a world-famous figure. By the mid-1930s, Rogers was adored by the American people. He was the leading political wit of the Progressive Era, and was the top-paid Hollywood movie star at the time. Rogers died in 1935 with aviator Wiley Post, when their small airplane crashed near Barrow, Alaska.
 
His vaudeville rope act led to success in the Ziegfeld Follies, which in turn led to the first of his many movie contracts. His 1920s syndicated newspaper column and his radio appearances increased his visibility and popularity. Rogers crusaded for aviation expansion, and provided Americans with first-hand accounts of his world travels. His earthy anecdotes and folksy style allowed him to poke fun at gangsters, prohibition, politicians, government programs, and a host of other controversial topics in a way that was readily appreciated by a national audience, with no one offended. His short aphorisms, couched in humorous terms, were widely quoted: “I am not a member of an organized political party. I am a Democrat.”
   
Google Books
The Yale Book of Quotations
Edited by Fred R. Shapiro
New Haven, CT: Yale University Press
2006
Pg. 541 (Modern Proverbs):
“Your guess is as good as mine.”
N. Y. Times, 4 Aug. 1907
 
Google Books
Radio Broadcasts of Will Rogers
By Will Rogers
Edited by Steven K. Gragert
Stillwater, OK: Oklahoma State University Press
1983
Pg. 158:
I would never make an economist in the world. An economist is a man that can tell you anything about — he’ll tell you what can happen under any given conditions, and his guess is liable to be just as good as anybody else’s, too.
 
27 December 1992, Los Angeles (CA) Times, “Pessimistic Economists Generally Hit Target” by Anne Michaud and Chris Woodyard, Business, pg. D5:
“An economist is a man that can tell you what can happen under any given condition and his guess is liable to be as good as anybody else’s too.”—Will Rogers
   
Will Rogers Today
Monday, December 01, 2008
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“To be perfectly frank with you, there’s quite a few problems agitating the country that I don’t hardly know anything about. I would never make an Economist. An Economist is a man that can tell you what can happen under any given conditions. And his guess is liable to be just as good as anybody else’s.” Radio, May 26, 1935
 
“I don’t know anymore about this thing than an economist does, and God knows, he don’t know anything.” Radio, April 7, 1935