Internal Revenue Service (IRS) computers each year churn out tens of thousands of pages of statistics relating to all phases of the bureau's operations. But IRS considers much of that data confidential.

Nearly six months ago, on Oct. 24, 1973, The Inquirer submitted a request to IRS Commissioner Donald C. Alexander for a variety of statistical material.

While some of the material sought was later obtained from published reports, IRS either refused or failed to provide statistics concerning the agency's auditing and collection procedures.

As a result, the statistics used in the accompanying articles and the articles that will follow in this series, "Auditing the IRS," came from two sources:

 Published IRS reports such as the "Statistics of Income," the "Commissioner’s Annual Report," and "The Audit Story."

 Documents obtained by a suburban Seattle, Wash., couple, Mr. and Mrs. Philip H. Long, after they filed a lawsuit against IRS under the Federal Freedom of Information (FOI) Act.

The couple has been waging a running campaign against IRS since 1969, when Long, who operates several family real estate businesses, was hit with what he considered to be an unfair tax bill of $38,000 following an audit.

While they pursued their case in the Tax Court, the Longs – and especially Mrs. Long, who has an affinity for statistics – flooded IRS with requests for specific documents.

Mrs. Long, who is studying for her doctorate in sociology at the University of Washington, said many of the requests were denied until they won their lawsuit under the FOI Act in August 1972.

Then last summer, apparently as a result of an IRS oversight, the Longs received a copy of a computer printout with the results of an audit program on 1971 tax returns.

Although it wasn't labeled as much, the program turned out to be the Taxpayer Compliance Measurement Program (TCMP), a highly secret study that IRS has been making for 10 years now, measuring compliance with the tax laws by different income groups.

Even though the couple has won one FOI legal action, Mrs. Long says that beginning last September, requests for audit, collection and appeal statistics generally have gone unanswered.

In some of the statistical tables used in the series, The Inquirer made its own estimates, relating IRS data obtained by the Longs to material in public IRS reports.

In addition to those statistics bearing directly on IRS internal operations, Inquirer reporters also:

 Sifted through more than 20,000 federal tax lien notices filed in New York city, Philadelphia, Chicago and Los Angeles.

 Culled information from more than 30,000 pages of records and transcripts of proceedings in both state and federal courts in nearly two dozen different jurisdictions across eight states.

 Examined more than 5,000 pages of other legal documents, including probate reports, medical-licensing records, mortgage, deeds, marriage licenses, transcripts of hearings conducted by state regulatory agencies and United States Senate committee records.