The Post, in its editorial April 4, seems to have been misled in many ways by the Andrew Hacker article it reprinted ("The Big Census Is a Big Mistake," Outlook, March 29). Hacker touts the great accuracy of the Census Bureau's sample surveys and argues that they can give us better information for far less money and trouble than the attempt at counting everyone. He and The Post appear unaware that the Census Bureau has no way of taking accurate samples of the national population without the decennial total enumeration of the population to sample from.

Hacker and The Post also advocate eliminating questions that make it possible for the Census Bureau to adjust its samples continuously during the long period between censuses so that the samples can represent the national population with fair accuracy. The bureau can do this only on the basis of information on people's births, deaths, marriages and moves, in the detail that only the decennial census provides.

The Post and Hacker attribute current public unhappiness with the Census to its asking more questions -- and more difficult and intrusive ones. The truth is that the questionnaries have gotten shorter, less time-consuming and less burdensome. The most elaborate questionnaires (very long forms asked, incidentally, of every household) were those of the censuses during the second half of the 19th century -- the era of "rugged individualism," not the New Deal, Fair Deal or the Great Society.

The biggest recent changes have been made to achieve economy. Until 1970, a census-taker came to everyone's door. In 1980, the census Bureau aimed at vast savings by having 80 percent of the forms completed by mail. Interviewers armed with elaborate instructions and explanations avoid difficulties, misunderstandings and complaints to which the simplifications of a self-completed questionnaire are vulnerable. Many thousands of tests were done to design a do-it-yourself form that would be easy for most people.

But the Census Bureau knows that some people can have difficulty with some or all of the questions. No one has to fill out the form without help from a census-taker if he can't or doesn't want to do it himself. If he simply fails to mail back the form or sends it in incomplete, the bureau phones or sends someone around to help. The penalty is that he is among the taxpayers who pay for the census worker's time. We all will be paying dearly for visits to people who were dissuaded from mailing in their forms by ill-informed attacks on the census such as those in The Post.

Hacker and The Post also foster an elementary misunderstanding of what the census is about. They ask why it should be any of the government's business to know about my marriage, or my ethnic background, or how I earn my living, or where I lived before I moved here. Their question itself is a fallacy. The Census Bureau does not want to know these things about me or thee, individually; it is asking about us -- spelled "U.S." The census is nothing less than We, the People, wanting to know about We, the People of the United States.

No one may use census information on an individual person except that person -- at least not until 72 years later, when historians and genealogists may have a go at it. Why, of all records on persons, should that which is most protected by law and historically that most inviolate of abuse of confidentiality and privacy be the one we are told should be so "disquieting"?

There are no questions asked in the census that have not met the test of years of hearings and citizen discussions all over the country. The limit on what items get into the census is not set by how vital for the nation it would be to have the information. Rather, that limit is set by a sense of the will of the public to lend its time to this public purpose. It rests upon judgments by responsible congressmen of how sturdy that will is and the understanding of purpose on which it depends. These judgments have to anticipate the derision and bugbears expected from those ever ready to deplore government and all its works.

For instance, The Post editorial asks, scoffingly, why the Census should care whether a woman's marriage ended by the death of her husband. Let The Post ask the Social Security or Veteran's Administrations how many billions of dollars off pension-fund estimates would be without this and other marriage and divorce statistics afforded by the decennial census.

To argue, as The Post and Hacker do, that census data are used primarily by private business interests and therefore business users should pay for the whole census is heedless of the facts with regard to who uses census data, how they use it and who pays whom how much for various kinds of uses, and the very nature of such information as a commodity.

The census is used extensively by every level of government, by education, by the sciences -- in fact, directly or indirectly by everyone in the society. Although there are user charges for many specific uses, for most of the costs and benefits of the census there is no earthly way of charging for all individual uses. Every respectable economic theory recognizes that certain kinds of information cannot be treated other than as "public goods," else either no one would have any of that good at all, or all would pay more for far less of it. That is why censuses are among various general information functions that in all nations at all times are fulfilled by the state. It is up to the tax system to pay for goods of general social value proportionate to the stake each person and business has in the society.

Most important, what manner of a political science is this that the political scientist Hacker espouses and The Post adopts? Can either imagine a great nation continuing to function if the duties of citizenship are somehow overstrained when citizens are asked once every 10 years to give to the Census Bureau as little as 10 minutes or as much as an hour? The average person probably will not spend as much as two or three hours answering census questions during an entire lifetime. Is there such decay of civic spirit that this effort should be taken as a vexing burden?

If so, no wonder the United States is at a disadvantage relative to a country such as Japan, which celebrates "Statistics Day" and in which schoolchildren have special studies and contests for "Statistics Week." The Japanese have a better sense of the current era as "the information Revolution" and a recognition of the kinds of information that are civic goods, not private ones that can be readily bought or sold.

For good reason, the American people have been repelled by those nations that in this century have elevated collective purposes over individual rights and interests. For good reason, too, many have been repelled when and where they have seen collectivistic excess in their own country. There is good reason to be concerned that the reaction may have become to promiscuous and unthinking. We should begin to be worried when we have to ask if we can count on us.