Moderates were less likely than both liberals and conservatives to propose an amendment on a bill in which the amendment tree was filled. We also see some evidence of positive control from the Democratic leadership as there are fewer amendments submitted to the congressional record from liberals than there are conservatives. This supports the notion that senators use the ability to submit amendments as a method to register their displeasure with both the legislation and the process. Interestingly however, moderates are not using the procedure to register their displeasure with the legislation or the process, suggested that they are either okay with the substance of the legislation, or that they are fully entrusting the party leadership. Still, this is a descriptive cut of the data, and requires a more rigorous look. Table 1 summarizes the results of a negative binomial regression predicting the number of amendments submitted by Republicans when the amendment tree was filled. [Insert Table 1 here] The results of the negative binomial regression largely confirm the descriptive results. The distance from the middle variable is significant at the .1 level and positive, suggesting that the further a senator sits from the ideological center of the chamber, the greater the number of amendments they submit. Figure 2 illustrates the change in predicted number of amendments by the ideological distance from the center. The difference between the most moderate Republican and the most conservative Republican is approximately one amendment. [Insert Figure 2 here] Despite the logic of using the amendment process to signal constituents, the variables measuring senators in the election cycle were not significant. Similarly, retiring senators and bill sponsors, did not propose significantly more or less amendments. Vulnerability also had no
Moderates were less likely than both liberals and conservatives to propose an amendment on a bill in which the amendment tree was filled. We also see some evidence of positive control from the Democratic leadership as there are fewer amendments submitted to the congressional record from liberals than there are conservatives. This supports the notion that senators use the ability to submit amendments as a method to register their displeasure with both the legislation and the process. Interestingly however, moderates are not using the procedure to register their displeasure with the legislation or the process, suggested that they are either okay with the substance of the legislation, or that they are fully entrusting the party leadership. Still, this is a descriptive cut of the data, and requires a more rigorous look. Table 1 summarizes the results of a negative binomial regression predicting the number of amendments submitted by Republicans when the amendment tree was filled. [Insert Table 1 here] The results of the negative binomial regression largely confirm the descriptive results. The distance from the middle variable is significant at the .1 level and positive, suggesting that the further a senator sits from the ideological center of the chamber, the greater the number of amendments they submit. Figure 2 illustrates the change in predicted number of amendments by the ideological distance from the center. The difference between the most moderate Republican and the most conservative Republican is approximately one amendment. [Insert Figure 2 here] Despite the logic of using the amendment process to signal constituents, the variables measuring senators in the election cycle were not significant. Similarly, retiring senators and bill sponsors, did not propose significantly more or less amendments. Vulnerability also had no
Filling%20the%20Amendment%20Tree_WPSA2017.docx