Wacquant notes that underclass status is imposed on urban blacks from outside and above them (e.g., by journalists, politicians, and academics), stating that "underclass" is a derogatory and "negative label that nobody claims or invokes except to pin it on to others". And, although the underclass concepts is homogenizing, Wacquant argues that underclass imagery differentiates on gender lines, with the underclass male being depicted as a violent "gang banger", a physical threat to public safety, and the underclass female being generalized as "welfare mother" (also see welfare queen), a "moral assault on American values". Homogenizing a heterogeneous group The concept of 'the ghetto' and 'underclass' has also faced criticism empirically. Research has shown significant differences in resources for neighborhoods with similar populations both across cities and over time. This includes differences in the resources of neighborhoods with predominantly low income and/or racial minority populations. The cause of these differences in resources across similar neighborhoods has more to do with dynamics outside of the neighborhood. To a large extent the problem with the 'ghetto' and 'underclass' concepts stem from the reliance on case studies (in particular case studies from Chicago), which confine social scientist understandings of socially disadvantaged neighborhoods. Proposed replacement terms The charges against underclass terminology have motivated replacement terms. For example, William Julius Wilson, sympathetic to criticisms brought against underclass terminology (particularly those criticisms posited by Gans), begins to replace his use of the term underclass with "ghetto poor" during the early 1990s. For Wilson, this replacement terminology is simply an attempt to revamp the framing of inner-city poverty as being structurally rooted. He states, "I will substitute the term 'ghetto poor' for the term 'underclass' and hope that I will not lose any of the subtle theoretical meaning that the latter term has had in my writings." See also References 1960s neologisms Measurements and definitions of poverty Social classes