Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 How Low Can We Go? Problems with ZIP Code Level Analyses Lance Miller, MA Andrea Rodriguez, MS San Bernardino County Department of Public Health

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Presentation Overview Problem statement Purpose San Bernardino County examples Muscoy ZIP code Conclusions Solutions

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Problem Statement Public health departments use ZIP code level analysis to identify areas where program resources are needed most Flawed source data can lead to erroneous conclusions and inaccurately targeted public health interventions

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Purpose Present two problems the San Bernardino County Public Health Department has encountered with ZIP code level analysis Discuss possible solutions to these problems, likely faced by state and local health agencies nationwide

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 The Muscoy Problem Where the heck is Muscoy?

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Muscoy, California

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 About Muscoy Unincorporated area Population in 2000: 9,000 residents Land area: 2.9 sq. miles Demographics Educational attainment Unemployment Income and poverty

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Why Muscoy? Lack of infrastructure Increase in violent crime Restless residents Call for community needs assessment }

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Muscoy Needs Assessment Resident survey Census data Birth outcomes Cause of death data 10 births 7 deaths

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Muscoy is within 92407

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 What else is in 92407? Actual city name is San Bernardino Acceptable city names include Arrowhead Farms, Devore Heights, Muscoy, and Verdemont Are people using “San Bernardino, 92407” when they truly reside in the area of Muscoy? How will I investigate this???

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Geocoding! Using GIS software to convert street addresses into latitude and longitude coordinates Makes locating addresses and viewing multiple locations on a map instantly possible

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Geocoding… Geocoding is a must if we want to examine births and deaths in Muscoy Teen birth events Smaller data set – more manageable Data exploration

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Startling Results ZIP code results: Less than 5 births to teen female residents of Muscoy Geocoded results: 40 births to teen female residents of Muscoy That’s well over 8 times as many births!!!

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Is this an isolated incident? NO! During presentation preparation, we discovered something similar happened before… Routine vital stats report for county health officer led to investigation of extremely high teen birth rate in ZIP code 92401

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 How the Study Began

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Routine Report Finding Mother’s residenceTeen birth rate California46.6 San Bernardino County58.1 ZIP code Note:Teen birth rate defined as number of live births to mothers aged years per 1,000 female population aged years. Sources:1. California Department of Health Services, Birth Files. 2. U.S. Census Bureau, 2000 Census, Summary File 1, Table P14. Prepared by San Bernardino County Department of Public Health.

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Health Officer’s Question Is high teen birth rate: artifact of data, or real phenomenon? To answer: Geocoded all births indicating residence What zip code was each birth really in (according to mapped street address)?

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Where is ZIP code 92401?

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Where is ZIP code 92401?

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Mapped teen births reported as Birth in Birth not in 92401

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Findings Actual ZIP code determined by mapping Births (56%) Other ZIP code19 (44%) Of 43 birth certificates indicating 92401:

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Findings Number of teen births in Teen birth rate 43 births (birth certificate data) Corrected: 24 births (mapped addresses) Note:Teen birth rate defined as number of live births to mothers aged years per 1,000 female population aged years. Sources:1. California Department of Health Services, Birth Files. 2. U.S. Census Bureau, 2000 Census, Summary File 1, Table P14. Prepared by San Bernardino County Department of Public Health.

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Health Officer’s Conclusions “Perhaps … zip codes are too small to do detailed … analyses” “We … have used zip code data … which may have been misleading to some degree if the data at this level is really so unreliable” “Given all these analysis problems, should we expend program resources targeted to this area?” Source: Thomas Prendergast, MD, MPH, personal correspondence with Evelyn Trevino, April 2003.

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Conclusions Cannot rely on ZIP codes alone for accurate geographic analysis Data entry error The nature of places In order to make valid conclusions, residence street addresses must be geocoded

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Solutions Good: START GEOCODING! Better: Birth and death events geocoded at the state level Best: Address validated and assigned coordinates at point of entry Essential to all: Understanding the importance of accurate data collection

Improving Security, Systems, and Statistics San Diego, CA June 4 th – 8 th, 2006 Our Contact Information Lance Miller, Statistical Analyst (909) Andrea Rodriguez, Statistical Analyst (909)