Updated 17 September 2015

This updated release of the DW-NOMINATE scores for the 1

"Measuring Bias and Uncertainty in Ideal Point Estimates via the Parametric Bootstrap."

"Measuring Bias and Uncertainty in DW-NOMINATE Ideal Point Estimates via the Parametric Bootstrap."

As Poole and Rosenthal explain in

In the House scaling, the second dimension weight is 0.3988 and the Beta parameter (proportional to 1/s where s is the standard deviation of the error) is 7.833. The correct classification was 87.78 percent with an APRE of 0.638 and a geometric mean probability of 0.761. The corresponding values for the Senate scaling are .5638 and 10.1105, for the second dimension weight and Beta, respectively. The correct classification was 86.1 percent with an APRE of 0.591 and a geometric mean probability of 0.744.

In order to calculate distances from the DW-NOMINATE scores you must multiply the second dimension by the weight parameter. To calculate the choice probabilities you must apply both the second dimension weight and the Beta parameter.

If you have used previous releases of the DW-NOMINATE scores please go to the Current vs. Past Releases of DW-NOMINATE Scores page. The scores computed for the 1

Please note that the House files now contain scores for most Presidents. For Presidents prior to Eisenhower these are based on roll calls corresponding to Presidential requests. These roll calls were compiled by an NSF project headed by Elaine Swift ( Study No. 3371, Database of Congressional Historical Statistics, 1789-1989). Many of these scores are based upon a small number of roll calls

If you have questions or need help with these files please send us e-mail at jblewis@ucla.edu (Jeff Lewis) or ktpoole@uga.edu (Keith Poole).

To see a QuickTime Movie of the DW-NOMINATE scalings download this movie file:

Two Dimensional Movie of the 1

The format of the legislator files is:

1. Congress Number 2. ICPSR ID Number: 5 digit code assigned by the ICPSR as corrected by Howard Rosenthal and myself. 3. State Code: 2 digit ICPSR State Code. 4. Congressional District Number (0 if Senate) 5. State Name 6. Party Code: 100 = Dem., 200 = Repub. (See PARTY3.DAT for a full set of codes of minor and historical parties) 7. Name 8. 1st Dimension Coordinate 9. 2nd Dimension Coordinate 10. 1st Dimension Bootstrapped Standard Error 11. 2nd Dimension Bootstrapped Standard Error 12. Correlation Between 1st and 2nd Dimension Bootstrapped Estimates over the 1000 trials (for computing the ellipsoid of estimated points) 13. Log-Likelihood 14. Number of Votes 15. Number of Classification Errors 16. Geometric Mean Probability The format of the roll call files is: 1. Congress Number 2. Roll Call Number 3. "H" if House, "S" if Senate 4. Number of Yeas 5. Number of Nays 6. Month of Roll Call 7. Day of Roll Call 8. Year of Roll Call 9. Number Correctly Classified 10. Predicted Yea/Actual Yea 11. Predicted Yea/Actual Nay 12. Predicted Nay/Actual Yea 13. Predicted Nay/Actual Nay 14. Proportion Correctly Classified (#9 divided by #4 + #5) 15. Proportional Reduction in Error (PRE) -- (Min. on RC - Error)/Min. on RC 16. Geometric Mean Probability 17. Spread on 1st Dimension -- if the roll call was not scaled, there 18. Midpoint on 1st Dimension -- are 0.000's in all four fields 19. Spread on 2nd Dimension -- 20. Midpoint on 2nd Dimension --

Legislator Estimates 1

Legislator Estimates 1

Legislator Estimates 1

Legislator Estimates 1

Legislator Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 83

Roll Call Estimates 83

Senator Estimates 1

Senator Estimates 1

Senator Estimates 1

Senator Estimates 1

Senator Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

Roll Call Estimates 1

NOMINATE Data, Roll Call Data, and Software

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