The following appeared in a recommendation from the planning department of the city of Transopolis. "Ten years ago, as part of a comprehensive urban renewal program, the city of Transopolis adapted for industrial use a large area of severely substandard

The planning department for the city of Transopolis recommends, as part of its urban renewal plan, that the city convert a certain residential area for industrial use and relocate residents from that area to nearby unoccupied housing. To support this recommendation, the planners point out that ten years ago the city converted an area of substandard housing on the other side of town, near a freeway, for industrial use, and that afterwards that area's crime rate declined while the city's overall property-tax revenue increased. I fred the recommendation specious on several grounds.

To begin with, the recommendation relies on two poor assumptions about the effects of the freeway-area conversion. One such assumption is that the freeway-area conversion caused the decline in that area's crime rate. The mere fact that the conversion occurred before the decline does not suffice to prove that the conversion caused the decline. Perhaps the true cause was some unrelated development--such as a new city-wide "tough-on-crime" policy or improvements in police training. Another such assumption is that the increase in overall property-tax revenue indicates an increase in tax revenue from properties in the freeway area. Perhaps property-tax revenue from the converted properties remained the same, or even declined, after the conversion, and that the city's overall property-tax revenue increase was attributable to properties located elsewhere in the city. For that matter, perhaps the city raised its property-tax rates shortly after the conversion. In short, without ruling out alternative explanations for the developments that came after the freeway-area conversion, the planners cannot convince me that the conversion was responsible for those developments.

Even if the evidence turns out to substantiate the two foregoing assumptions, the recommendation further assumes that the proposed conversion would carry the same results as the freeway-area conversion. Yet key differences between the two areas might undermine the analogy. For example, perhaps the properties surrounding the ones converted in the freeway area were not residential. Common sense informs me that crimes such as burglary and robbery are less likely in areas where few people reside. Since at least some nearby housing is available for residents displaced by the proposed conversion, this conversion might not result in any significant decline in the area's crime rate. At the same time, unless unoccupied nearby housing can accommodate all displaced residents, the conversion might create a homelessness problem, thereby undermining the city's objectives.

Finally, the recommendation assumes that all conditions bearing on whether residential to-industrial conversions would help renew Transopolis have remained unchanged over the past ten years--and will continue unchanged in the foreseeable future. Yet, perhaps Transopolis had more and better housing for displaced residents ten years ago than today. Or perhaps Transopolis would have more trouble finding occupants for additional industrial buildings today than it did ten years ago. Indeed, a myriad of factors---including the reg4onal and national economy, demographic shifts, and political influences--might explain why an urban-renewal program that had a Salutary impact on Transopolis' crime rate and property-tax revenues in the past might nevertheless not revitalize the city today, or in the future.

In sum, the planners' recommendation is largely unfounded. To bolster it they must provide clear evidence that the freeway-area conversion contributed to the decline in that area's crime rate and to the city's overall property-tax revenue increase. To better assess the argument I would need to know what other changes have occurred in the city that might explain those developments. Finally, to better assess the proposed plan's chances of success I would need to compare the circumstances surrounding the decline in the area slated for conversion with the decline in the freeway area prior to its conversion.