A panel of National Journal editors and reporters initially compiled a list of key congressional roll-call votes for 2000, and classified them as related to economic, social, or foreign policy. Roll-call data were drawn from the Congressional Record and Congressional Observer Publications at www.proaxis.com/cop, a private legislative tracking company.

Members were ranked from the most liberal to the most conservative in each issue area. These rankings were used to assign liberal and conservative percentile ratings to all members of Congress.

The liberal percentile score means that the member voted more liberal than that percentage of his or her colleagues in that issue area in 1999. The conservative figure means that the member voted more conservative than that percentage of his or her colleagues.

For example, a House member in the 30th percentile of liberals and the 60th percentile of conservatives on economic issues voted more liberal than 30 percent of the House and more conservative than 60 percent of the House on those issues and was tied with the remaining 10 percent. The scores do not mean that the member voted liberal 60 percent of the time and voted conservative 30 percent of the time.

Percentile scores can range from a minimum of 0 to a maximum of 99. Some members, however, voted either consistently liberal or consistently conservative on every roll call. As a result, there are ties at both the liberal and the conservative ends of each scale. For that reason, the maximum percentiles are usually less than 99.

The votes in each issue area were subjected to a principal components analysis, a statistical procedure designed to determine the degree to which each vote resembled other votes in the same category (the same members tending to vote together).

Seven of the 102 votes (four Senate and three House) were dropped from the analysis because they were statistically unrelated to others in the same issue area. These typically were votes that reflected regional and special-interest concerns rather than general ideology.

The analysis also revealed which yea votes correlated with which nay votes within each issue area (members voting yea on certain issues tended to vote nay on others). The yea and nay positions on each roll call were then identified as conservative or liberal. Each roll-call vote was assigned a weight from 1 (lowest) to 3 (highest), based on the degree to which it correlated with other votes in the same issue area.

A higher weight means that a vote was more strongly correlated with other votes and was therefore a better test of economic, social, or foreign policy ideology. Data processing and statistical analysis were performed by Information Technology Services of the Brookings Institution.

The votes in each issue area were combined in an index (liberal votes as a percentage of total votes cast, with each vote weighted 1, 2, or 3). Live pairs were counted as votes.

Absences and abstentions were not counted; instead, the percentage base was adjusted to compensate for missed roll calls. A member who missed more than half the votes in any issue category was scored as "missing" in that category (shown as an asterisk [*] in the voting tables).

For this reason, two House members are missing ratings for 2000: Reps. J. Dennis Hastert, R-Ill., who, as Speaker, did not usually vote, and Bruce Vento, D-Minn., who died Oct. 8, 2000, after a battle with cancer.

• 7/H.R. 2005 -- Limit liability lawsuits against manufacturers of durable goods. Feb. 2. (222-194) C-3
• 15/H.R. 6 -- Eliminate the so-called marriage penalty on income-tax filers. Feb. 10 (268-158) C-3
• 25/H.R. 2366 -- Restrict punitive damages in product-liability suits against small businesses. Feb. 16. (221-193) C-3
• 43/H.R. 3846 -- Increase the minimum wage by $1.00 in two years, rather than three years as reported by the House committee. March 9. (246-179) L-3
• 55/H.R. 2372 -- Expedite federal court handling of "property rights" cases dealing with local land use. March 16. (226-182) C-2
• 63/S.1287 -- Complete the licensing activities for a nuclear-waste storage site at Yucca Mountain, Nevada. March 22. (253-167) C-2
• 70/H.Con.Res.290 -- Substitute Congressional Black Caucus version of the fiscal 2001 budget resolution, including transfer of spending from defense to domestic programs. March 23. (70-348) C-1
• 73/H.Con.Res.290 -- Substitute Conservative Action Team version of the fiscal 2001 budget resolution, including domestic-spending freeze and larger tax cuts. March 23. (78-339) L-1
• 74/H.Con.Res.290 -- Substitute Democratic version of the fiscal 2001 budget resolution, including steps to extend Social Security solvency. March 23. (184-233) C-3
• 75/H.Con.Res.290 -- Approve the fiscal 2001 budget resolution. March 23. (211-207) C-3
• 119/H.J.Res.94 -- Approve a constitutional amendment to require a two-thirds vote in the House and Senate to raise taxes. April 12. (234-192; failed to receive the required two-thirds) L-3
• 127/H.R. 4199 -- Abolish the tax code in 2004, with recommendation that Congress approve a new code by that time. April 13. (229-187) C-3
• 179/H.R. 701 -- Establish a land-conservation program funded by royalties on oil and gas drilling on federal lands. May 11. (315-102) L-1
• 250/H.R. 4577 -- Strike ban on federal standard for ergonomic protection. June 8. (203-220) C-3
• 254/H.R. 8 -- Phase out estate and gift taxes from the income tax code. June 9. (279-136) C-3
• 281/H.R. 4578 -- Eliminate restrictions on various Interior Department programs. June 15. (243-177) L-3
• 305/H.R. 4635 -- Delay until 2001 Environmental Protection Agency enforcement of its stricter national ambient air quality standards. June 21. (225-199) C-2
• 357/H.R. 4680 -- Provide voluntary prescription-drug coverage through insurance companies for Medicare beneficiaries. June 28. (217-214) C-3
• 450/H.R. 4865 -- Repeal the 1993 tax increase on Social Security beneficiaries. July 27. (265-159) C-3
• 458/H.R. 8 -- Override President Clinton's veto of phase-out of estate and gift taxes. Sept. 7. (274-157; failed to receive the required two-thirds) L-3
• 467/H.R. 4986 -- Revise taxation of Foreign Sales Corporations. Sept. 13. (315-109) C-1
• 560/H.R. 2614 -- Approve conference report with retirement and savings tax cuts, plus minimum-wage increase of $1.00 per hour. Oct. 26. (237-174) C-3

• 5/H.R. 1838 -- Strengthen U.S. military relations with Taiwan. Feb. 1. (341-70) C-1
• 85/H.R. 3908 -- Increase by $4 billion supplemental spending for the Pentagon. March 29 (289-130) C-1
• 88/H.R. 3908 -- Prohibit the use of $40 million for a referendum in Vieques, Puerto Rico regarding the Navy's further use of the island training range. March 29. (183-232) L-2
• 89/H.R. 3908 -- Withhold 50 per cent of funding for military operations in Kosovo until the President certifies that NATO members have obligated certain funds. March 30. (200-219) L-1
• 193/H.R. 4205 -- Require burden-sharing targets for European nations to support military operations in Kosovo. May 17. (264-153) C-1
• 196/H.R. 4205 -- Terminate the Trident II submarine-launched ballistic missile program. May 18. (112-313) C-2
• 205/H.R. 4205 -- Bar federal guarantees for potential liability claims for accidents involving nuclear reactors provided to North Korea. May 18. (334-85) C-2
• 214/H.R. 4392 -- Require the Central Intelligence Agency to disclose its spending for intelligence activities. May 23. (175-225) C-3
• 397/H.R. 4811 -- Provide debt relief for heavily-indebted nations. July 13. (216-211) L-3
• 414/H.R. 4118 -- Bar forgiveness of Russia's debt until that nation closes its Cuban intelligence facility. July 19. (275-146) C-3
• 424/H.R. 4871 -- Drop enforcement of U.S. economic embargo of Cuba. July 20. (174-241) C-2
• 426/H.R. 4871 -- Drop sanctions on sales of farm commodities and medical supplies to Cuba. July 20. (301-116) L-1

• 101/H.R. 2418 -- Impose additional federal controls on organ-transplant programs. April 4. (275-147) C-1
• 104/H.R. 3660 -- Ban partial-birth abortions. April 5. (287-141) C-3
• 109/H.R. 1776 -- Allow religious organizations to compete for block grants in home-ownership program on the same basis as private organizations. April 6. (299-124) C-2
• 115/H.R. 4051 -- Authorize block grants to states that require mandatory minimum sentences for the use or possession of firearms while committing a crime. April. 11. (358-60) C-1
• 203/H.R. 4205 -- Permit military-service members and their families to have abortions in Defense Department facilities overseas. May 18. (195-221) C-3
• 282/H.R. 4578 -- Reduce funds for the National Endowment for the Arts. June 15. (152-256) L-2
• 295/H.R. 4201 -- Limit Federal Communications Commission regulation of non-commercial religious broadcasters. June 20. (264-159) C-3
• 306/H.R. 4635 -- Bar Housing and Urban Development Department funding of its safer-guns program with local governments. June 21. (218-207) C-3
• 317/H.R. 4690 -- Reduce funding for violent offender imprisonment and truth-in-sentencing grants. June 22. (184-226) C-2
• 318/H.R. 4690 -- Strike ban on federal funds for abortion services for female federal prisoners. June 22. (156-254) C-3
• 319/H.R. 4690 -- Permit the Justice Department to receive funds from other federal agencies to support its litigation against tobacco companies. June 23. (215-183) L-2
• 324/H.R. 4690 -- Bar the Justice Department from implementing its agreement with Smith and Wesson Co. on gun-safety measures. June 26. (196-201) L-3
• 373/H.R. 4461 -- Prohibit the Food and Drug Administration from testing or approving abortion-inducing drugs such as RU-486. July 10. (182-187) L-3
• 396/H.R. 4811 -- Remove anti-abortion restrictions on U.S. aid for international family planning programs. July 13. (206-221) C-3
• 422/H.R. 4871 -- Strike prohibition of abortion coverage under federal employees health benefit program. July 20. (184-230) C-3
• 455/H.R. 4678 -- Prohibit religious requirements for grant recipients in a fatherhood program. Sept. 7 (163-257) C-3
• 471/H.R. 4205 -- Instruct conferees to accept provision broadening coverage of federal hate crimes. Sept. 13. (232-192) L-3
• 472/H.R. 4942 -- Bar possession of tobacco products by minors in the District of Columbia. Sept. 14. (265-155) C-2
• 473/H.R. 4942 -- Expand restrictions on the District of Columbia needle-exchange program. Sept. 14. (239-181) C-3