I know ballpark figure means estimate, but I don't understand why it means estimate. Literally, how does ballpark make figure an estimate? Ballpark means a baseball stadium or field from google definition.
From Paul Dickson, The Dickson Baseball Dictionary (1989):
ballpark figure n. EXT[ernal use:] A rough estimate. This has [a] decidedly odd connection to baseball given that most figures having to do with the game (batting averages, earned run averages and other statistics) are relentlessly precise. Lexicographer Stuart Flexner is quoted by William Safire on its evolution in the book I Stand Corrected: "Our Random House dictionary citation files show the term first started out as in the ballpark (1962), as when talking about figures, estimates, etc., with "I hope that's in the ballpark.' Then, in 1968, we first recorded ballpark figure from The Seattle Times."
So according to Flexner, via Safire, "in the ballpark" to mean "approximately" goes back only to 1962.
The first metaphorical (non-baseball) use of "in the ballpark" in the sense of "approximately correct or accurate" that an Elephind search finds is from "The Supreme Court Mallory Ruling," the Detroit [Michigan] Tribune (November 7, 1964):
The speaker was critical of the Supreme Court Mallory ruling, saying the court "wasn't even in the ballpark" when it FREED A "CONFESSED RAPIST" because too much time had elapsed between the man's arrest and his arraignment on formal charges.
However, "in the ballpark" in the sense of "near success" appears in a cartoon called "Freckles and His Friends," in the Sweetwater [Texas] Reporter (August 20, 1951), where a youth sitting some distance outside the doorway to a curio shop tells Freckles and another buddy:
"Get to first base with her? I didn't even get in the ballpark!"
From this early example it seems very possible that "in the ballpark" originally meant something like "in the vicinity of a desired place" and that it subsequently evolved to mean, in effect, "close to an accurate number or prediction."
A Google Books search yields some other interesting early instances of "in the ballpark." From Review of the Space Program: Hearings Before the Committee on Science and Astronautics (1960) [combined snippets]:
Mr. BASS. Do you know how much?
Dr. DRYDEN. I have said that in the super booster program it will be in the "ballpark" area of another hundred million areas.
From Proceedings of the Power Reactor In-Core Instrumentation Meeting, Washington, D.C., April 28–29, 1960 (1961) [combined snippets]:
In reference to this Teleflex cable, I would like to say that we have not eliminated them from consideration on our project. They had some encouraging test runs at KAPL, as you have heard; although, it did not meet the requirements for the specific detector we were considering. They were in the ballpark. Teleflex has stated that they intended to do further development and testing on their current cable and at other independent laboratories. They are still a possibility.
Mr. Komsky: I think two and a half billion would be quite sufficient. As large as it sounds, it is simply getting in the ballpark of what we have learned from previous aid programs is necessary to get out of the aid business. It actually takes more aid to get out of the aid business. This is a hard thing to get across in many areas. Obviously it is difficult from a political standpoint, it is a long-range concept, and it is hard to sell a long-range concept.
Another interesting early metaphorical usage appears in a caption in "School Segregation Up North," in Ebony magazine (June 1962):
Picketing, like that in Chicago (l.) and Cleveland, protests Northern de facto school segregation. "No one will desegregate you except you yourselves," sociologist Saul D. Alinsky told an approving Chicago audience. "If you accept segregation, you will continue to have it. If you stay in the ballpark and keep trying, the game is yours."
Here, "stay[ing] in the ballpark" seems to mean something like refusing to give up or go away. This does not appear to be in the same line of usage that may connect "Freckles and His Friends" in 1951 to government hearings in 1960 and from there to the example in the Detroit Tribune in 1964, however.
If someone asks you how accurate some estimate of something is, you can say "it's in the right ballpark".
It's a way of saying the estimate was not especially wrong, but not especially accurate either, since a ballpark is really a fairly large area of land.
So a ballpark figure or ballpark estimate is an one that's "in the right ballpark".
Both in the ballpark and the closely related ballpark figure emerge in the mid- to late 1950s in the published proceedings of scientific conferences and government hearings exploring similar topics: peacetime nuclear power, the space race with the Soviet Union, and the money to pay for it all.
Given post-war America’s renewed passion for baseball and the almost exclusively male community of aerospace engineers and military scientists, it’s hardly surprising that a sports metaphor would be employed in either expression.
The earliest sources for both terms have a decidedly oral, even dialogical character: both conference discussion and government hearings were carefully protocoled and only mildly edited. Even remarks previously prepared, whether lecture or testimony, were designed for oral delivery.
This also helps explain the lag between this more ephemeral literature and other genres such as newspapers or popular fiction, which is likely the reason a number of online sources give a later date for the first attestation of the two expressions. The term ballpark figure, for instance, didn’t appear in Time Magazine until April 1974 (BYU Time Corpus), and even there, it’s in a direct quote.
The large dots above represent reactor costs. All of them are experimental reactors at the present time, and none of them are in the ballpark as far as competitive plant costs are concerned. The picture is a little more cheerful if you turn to over-all power costs. — Proceedings, Ohio Conference on the Peacetime Uses of Nuclear Energy and Radiation Safety, Columbus, 29 Aug. 1956, 23.
Representative VAN ZANDT [James E., R-PA]. Would you say $2 million is the money you needed in 1958 as a supplemental?
Colonel ARMSTRONG [Jack, Aircraft Reactors Branch, Atomic Energy Comm.]. I said I thought that if we get this additional money in 1959 we would probably need about a million more here in 1958 to build up to that effort. I hope I am not out of the ballpark. — “Outer Space Propulsion by Nuclear Energy,” House Subcommitte on Research and Development, Joint Committee on Atomic Energy, 22 Jan. 1958.
Colonel ARMSTRONG. If you can have power without any moving parts, you are really in the ballpark. Senator BRICKER [John W. R-OH]. With a good pitcher. — ibid., 23 Jan. 1958.
The “ballpark” figure has been extremely useful in estimating reliability of systems ... — IRE [Institute of Radio Engineers] National Convention Record 6/6-10, 1958, 170.
For example, at 250 miles altitude the period is 90 minutes, and this is in the ballpark as far as the orbits that have been achieved so far by the Russians and by us. The periods have run from 90 to 134 minutes. — John P. Hagen, “Satellite Tracking” (lecture), 29 April 1958, Problems of satellites and space operations; lecture series sponsored by Office of Naval Research, April-July 1958, pub. 1961.
While in the ballpark frequently locates a quantity or value, i.e., a ballpark figure, an estimate acceptable within a certain range or tolerance, Col. Armstrong‘s nuclear power with no moving parts puts a quality rather than quantity in the ballpark. Sen. Bricker’s quip also suggests the expression was not unknown to him. Armstrong also uses the opposite out of the ballpark when he doubts his own estimate.
House Review of the Space Program, Jan. 1960
A hearing on the expanding space program in the House of Representatives in late January 1960 offers further attestations — and one for a older expression which essentially vanished before the turn of the millennium:
Money is only one element of it and we use the money estimate in relation to the other factors in his proposal, principally to see if he is in the ballpark of sensible estimating. — “Review of the Space Program,” House Committee on Science and Astronautics, 22 Jan. 1960, 43.
Mr. Daddario [Emilio Q., D-CT]. How many people do you have involved in this space medicine field ?
Captain Phoebus [Clifford P., Dir., Astronautical Div., Bureau of Med. and Surg., Navy]. I would say in top-notch scientists scattered around these 6 laboratories there may be something in the ballpark of 75, in this vicinity. — “Review of the Space Program,” ibid., 49.
The Chairman [Overton Brooks, D-LA]. You are $50 million short from the original request, roughly.
Dr. Dryden [Hugh L., Dep. Admin., NASA]. It depends on the exact number that comes out of this study. I said of the order of $100 million. If it is $125 million or $75 million — I am just giving you a “ballpark” estimate of the order of magnitude. — ibid., 228.
A minute or so earlier, Dryden had used an older expression with the same meaning:
Dr. Dryden. As compared with the 957, we were allocated or allotted $802 million and there is still to come before you the requests resulting from this study for which I gave a “horseback” estimate of the order of $100 million. — ibid.
The horseback estimate dates at least to 1920:
It is estimated that the water front of New York is 500 miles In length, and with that liberality of margin characteristic of horseback estimates the cost of this improvement would be "from $50,000,000 to $100,000,000.” — New York Herald, 20 Dec., 1920, 10.
Though ballpark figure isn’t firmly established until the mid-70s (cf. Time above and this NGram) the expression shows signs of broadening in the 1960s. Even an Oregon congressman tries in the ballpark on for size:
Mr. PORTER [Charles O., D-OR]. Right now, at least 25 percent at the end of next year will be going through your hands, according to the Postmaster General, if his figures are in the ballpark, although I am not sure they are. — “Postal Rate Revision,” House Committee on Post Office and Civil Service, 26 May 1960, 382.
In reference to this Teleflex cable, I would like to say that we have not eliminated them from consideration on our project … although, it did not meet the requirements for the specific detector we were considering. They were in the ballpark. Teleflex has stated that they intended to do further development and testing on their current cable and at other independent laboratories. They are still a possibility. — Proceedings of the Power Reactor In-Core Instrumentation Meeting, Washington, D.C., April 28-29, 1960, pub. 1961.
I think Herb is in the ballpark. We have made outlandish guesses, too, as to what it costs and what happens, … — Proceedings of the Symposium on Uranium Carbides as Reactor Fuel Materials, Germantown MD, April 4, 1961.
MR. COLOMB: Do you have the measurement, just a number?
MR. HILL: Well, it drops from 5 down to 2.5 or 3.
MR. COLOMB: In a steel target?
MR. HILL: Yes, in a thin shell and in a one-inch stainless-steel capsule. This is sort of a ballpark number. — Conference on Light-Water-Moderated Research Reactors : held at Gatlinburg, Tennessee, June 11-14, 1962. Book 3 / Oak Ridge National Laboratory, 1963, 1256f.
Not all of that $7 billion could legitimately be handled that way or should be handled that way by any means. But this gives you a ballpark number as to what is involved. — House Appropriations Committee, 3 Mar. 1966, 607.
Mr. Seidman. We could certainly put forth an estimate of the staff time in the Bureau specifically allocated to this objective. … That is, with a pretty clear understanding that it would be an arbitrary allocation.
Mr. Conte. Well, call it a ballpark figure.
Mr. Seidman. Yes. About 25 professional and secretarial positions in the various offices and divisions of the Bureau are directly concerned with work primarily on management improvement. Varying amounts of time of other staff members is devoted to this work. A ballpark figure would be about 50 man-years for the Bureau as a whole. — ibid., 795.
Unless there are further instances of in the ballpark or ballpark figure lurking somewhere forgotten and undigitalized, the first attestations of ballpark estimate suggest an origin among engineers and scientists in the mid-50s who needed a precise — and at least initially clever — expression for imprecision. In the 1960s the expression began to move from jargon to the general language, where through the rest of the century its frequency steadily increased.
Probably an allusion to the relatively large field in the game of baseball and to the fact that baseballs are seldom hit out of the ballpark, but instead land anywhere within it.
The expression derives from earlier similar usages as in the ballpark, out of the ballpark:
From the AHD
This term alludes to a baseball field, which is always an enclosed space. The expression is basically an extension of the somewhat earlier in the ballpark, meaning within a reasonable range, and out of the ballpark, beyond a reasonable range. [Slang; late 1960s]
The Phrase Finder notes that:
The term has a decided odd connection to baseball given the most figures having to do with the game (such as batting averages and earned run averages) are relentlessly precise. Lexicographer Stuart Flexner is quoted by William Safire (I Stand Corrected, 1984) on its evolution: "Our Random House dictionary citation files show the term first started out as 'in the ballpark' , as when talking about figures, estimates, etc., with 'I hope that's in the ballpark.' Then, in 1968, we first recorded 'ballpark figure' from the Seattle Times."
From The New Dickson Baseball Dictionary by Paul Dickson.
NAL guaranteed Whalen an advance of $100,000, which is not bad for a first book. "The other bids were in the same ballpark," Whalen said. (San Francisco Examiner Book Week, March 28, 1965)
I think they accepted it as a guess. I thought it was a ball-park figure. (Wall Street Journal, June 7, 1967)