Some researchers believe that empirical evidence for the connection between disorder and crime is weak and overblown. Others argue that New York City’s success in reducing crime has been oversimplified and distorted and that the city’s significant decline in crime results from a complicated array of factors. Scholars in criminology regard the nationwide decline in crime rates over the last decade as a puzzle, of which broken windows is only a part. Research by Skogan, Harcourt, Taylor, Sampson, Eck, and Maguire have examined this issue. Kelling considers New York City to be the main example of the broken-windows theory. However, crime began to decline in the city several years before the policing innovations cited. In addition, crime declined in cities that did not use the techniques used in New York City. The debate over broken windows is a debate about ideology as much as it is about the effectiveness of a particular policy. The uncertainty regarding the reasons for the crime decline in New York City is typical of criminology due to the difficulty of conducting experiments on the impacts of different approaches to policing.