Firefighters Don't Cause Fires: LAHSA's 2009 Homeless Count

Last week, the Los Angeles Homeless Services Authority (LAHSA) released a report on their 2009 Greater Los Angeles Homeless Count. The report's main finding, that the homeless population in the cities covered by the Los Angeles Continuum of Care has dropped 38% since the last LAHSA-sponsored count in 2007, is counterintuitive, given the dramatic decline in the region's economic fortunes over the past two years. More accurate counting techniques may be responsible for the difference between the 2009 and 2007 reports as the authors write:

enhancements to the data collection process such as the increased number of volunteers, expansion of census tracts covered, and the reduction of possible counting biases have collectively enabled researchers to extrapolate more detailed information...

However, the authors downplay the role of the measurement strategy used in the 2009 report and make a bold claim:

While many factors likely contributed to this decline, it is important to acknowledge new and expanded programs implemented by the Los Angeles [Continuum of Care] network of housing and service providers.

The data presented in the report don't support this claim. Let's say measurement doesn't matter and the homeless population in the Continuum of Care's coverage area really has gone down 38% since 2007. The drop in homeless population says nothing about the success or failure of the providers' new and expanded programs. Just because these programs were implemented at the same time as a speculated decrease in the area's homeless population doesn't mean that the new programs caused the decrease by getting people off the streets and into new, self-sufficient lives.

Just because a person, agency, or program is present when an event occurs doesn't mean that he or she caused it. The title of this post is the classic example: firefighters are typically present when a fire occurs- does that mean that firefighters cause fires? Of course not, and we have statistical ways of showing that firefighters respond to fires. To prove a much less obvious conclusion, that new programs are responsible for a decline in the homeless population, LAHSA's researchers need to employ these techniques. The unlikely nature of a decline in homelessness during a recession necessitates good, solid evidence, not unsubstantiated claims.

(Photo by Lucas Janin)