Butler, Daniel M., Christopher F. Karpowitz and Jeremy C. Pope (2012), "A Field Experiment on Legislators’ Home Styles: Service versus Policy," Journal of Politics 74(2): 474-486. DOI: http://dx.doi.org/10.1017/S0022381611001708.
We conducted a field experiment involving roughly 1,000 letters sent by actual individuals to nearly 500 different legislative offices in order to test whether legislative offices prioritize service over policy in their home style. We find strong evidence that both state and federal legislative offices are more responsive to service requests than they are to policy requests. This pattern is consistent with the desire of legislators to gain leeway with their constituents in order to pursue their own policy goals. We also find that at the federal level Democrats prioritize service over policy more than Republicans and at the state level legislators who won by larger margins are more likely to prioritize service over policy. Finally, our results suggest that the decision to prioritize service occurs in how the office is structured. Among other things this suggests that legislators may be microtargeting less than is often supposed.
Link to article here.