8. Number of individuals in substance abuse clinics and/or treatment reporting income below the poverty line (nominal): This could show a direct correlation between poverty and substance abuse

9. Number of individuals in substance abuse clinics and/or treatment reporting they are homeless and/or have resulted to panhandling (nominal): This could show a direct correlation between homelessness, panhandling and substance abuse.

10. Number of individuals stopped for panhandling by the police: While the police usually do not arrest individuals for panhandling, police logs of individuals who are reprimanded for doing so, and under what circumstances (if the individual's circumstances indicated homelessness or substance abuse) could relevant if a pervasive pattern could be shown of the practice on a large scale.

11. Average of individuals at private substance abuse clinics vs. publically-supported treatment (ordinal): This would paint a portrait of how income can generate a different standard of care for the wealthy.

12. Number of individuals at private vs. government-funded substance abuse clinics who have been arrested for drug-related crimes: It is suggested that individuals who have 'means' and abuse drugs often are less harshly penalized by the legal system. The discrepancy between the two figures would suggest if there was a difference in terms of treatment, which might conversely affect the lives of poorer defendants...

Measuring the homeless population is also a challenge, given that homeless people often hide from authorities, for fear of being forced to enter a shelter. And panhandling, because it is illegal, yet the law is against panhandling seldom enforced, can be a difficult crime to track. Only by assessing a variety of statistics can a portrait of homelessness, drug abuse, poverty and the means individuals deploy to survive be ascertained. The picture is not likely to be complete but statistics should be validated with cross-referencing of other studies, preferably larger studies conducted longitudinally by nonpartisan sources.
References

Nationwide trends. (2010). National Institute of Drug Abuse. Retrieved June 19, 2010 at http://www.drugabuse.gov/infofacts/nationtrends.html

Morales, I. Number of homeless down, but homeless families up. (2010, June 16). AP News.

Retrieved June 19, 2010 at http://news.yahoo.com/s/ap/20100617/ap_on_go_ca_st_pe/us_hud_homelessness

What is the difference between categorical, ordinal, and interval variables? (2010). UCLA.

Retrieved June 19, 2010 at http://www.ats.ucla.edu/stat/mult_pkg/whatstat/nominal_ordinal_interval.htm