天山7-22

T-4-Q20
        天山-7-22

The violent crime rate (number of violent crimes
per 1,000 residents) in Meadowbrook is 60 percent higher now than it was four
years ago. The corresponding increase for Parkdale is only 10 percent. These
figures support the conclusion that residents of Meadowbrook are more likely to
become victims of violent crime than are residents of Parkdale.

The argument above is flawed because it fails to
take into account

1. Changes in the
        population density of both Meadowbrook and Parkdale over the past four
        years.
2. How the rate of
        population growth in Meadowbrook over the past four years compares to the
        corresponding rate for Parkdale
3. The ratio of violent to
        nonviolent crimes committed during the past four years in Meadowbrook and
        arkdale
4. The violent crime rates
        in Meadowbrook and Parkdale four years ago

应该选D，假设M城的crime rate四年前是10%，P城四年前是50%，则四年后M城crime rate为16%，P城为55%，P城的犯罪率在四年后依然比M城高，即使这四年的犯罪增长率M高于P，决定结果的除了变化的比率，还有变化的基数。

因为犯罪率的变化已经包含了人口变化的因素，所以不用考虑