Address Frames and Mail Surveysas Complements (or Alternatives)

to RDD Surveys

Michael W. Link, Michael P. Battaglia, Martin R. Frankel,

Larry Osborn, and Ali H. Mokdad

Second International Conference on Telephone Survey Methodology, Miami, FL

Problems Facing RDD SurveysGrowing NonresponseFrame coverage issues:

Households with no telephones (1.6%) Cell phone only households (3.7%) Households in zero-banks (3-4%)

Frame efficiency issues: Proliferation of telephone numbers Cell phone numbers in mixed-use exchanges

Other issues: Erosion of geographic specificity at state and

substate levels

Behavioral Risk Factor Surveillance System (BRFSS)

Monthly state-based RDD survey of health issues

50 states, District of Columbia, Puerto Rico, Guam, and Virgin Islands

300,000 adult interviews conducted in 2005

Faced with declining response rates

Need to identify best future design (frame & mode)

USPS Delivery Sequence File (DSF) as an alternative sampling frame

File contains All delivery point addresses serviced by USPS Identifies address type

Residential vs business City style vs PO box vs other types

Format conforms to USPS addressing standards

Initial assessments for survey use: Highest coverage in urban areas Potential for coverage to improve in rural areas

Potential Drawbacks of DSFUnknown level of coverage:

Excludes households with no USPS mail delivery Must purchase through list vendor (not USPS)

Updates/list maintenance may vary Some exclude addresses on request

Includes simplified addresses: City, state, zip code only

Other potential problems: Seasonal units, PO Boxes and multi-drop addresses

Key questions to addressHow do RDD and DSF-based mail surveys

compare in terms of: frame efficiency response rates respondent demographics Estimates on key health issues

Can DSF-based mail surveys reach households without telephones and cell phone-only households?

BRFSS 2005 DSF mail survey pilot

Six states: CA, IL, NJ, NC, TX, WA

Sampling frame: access to Delivery Sequence File (DSF) provided by Marketing Systems Group

Mode: mail survey with telephone verification for respondent selection

Mail survey fielded March 15-May 15, 2005

Compared to monthly RDD surveys from March-May, 2005

BRFSS 2005 DSF pilot: sample designProbability sample from DSF household frames in each

state

Excluded business addresses identified by USPS or Marketing Systems Group

Included seasonal units, vacant units, PO Boxes, throwback units, and drop point units

Stratified each state sample by county and address type

Drew 1,680 addresses per state using systematic random sampling

Split sample treatment groups

Postcard (after 7 days)

Second questionnaire mailing (after 2 weeks)

Surname on address label

Alternative within household selection methods: any adult (non-probability) next birthday all adults

Frame coverage assessment and characteristics

Percentage of Counties with >10% Under-coverage by State

0

10

20

30

40

50

60

NJ CA IL WA TX NC

% counties

with

>10% under-

coverage

Percentage of Counties with >10% Under-coverage by Pct. Urban

0

10

20

30

40

50

60

70

80

90

% counties

with

>10% under-

coverage

< 25% 25-49%

50-74%

75+%

% of adults in county living in urban area

BRFSS DSF Pilot:Types of Addresses

State

Address Type

City Style(%)

PO Box(%)

Seasonal Unit(%)

Vacant Unit(%)

Throw-back Unit(%)

DropPoint Unit(%)

California 91 8 <1 1 <1 <1

Illinois 87 5 0 3 <1 5

New Jersey 86 6 <1 1 <1 5

North Carolina

89 7 <1 2 <1 <1

Texas 89 8 <1 2 <1 <1

Washington 91 6 0 2 <1 <1

Response rates

Design factors and probability of completed interview from total cases

(adjusted odds ratios)

AOR (95% CI)

Address type Other type 1.00

City style 2.27 (1.74-2.95)

PO Box 1.83 (1.30-2.58)

Postcard sent No 1.00

Yes 1.12 (1.02-1.22)

Second Questionnaire No 1.00

Yes 1.58 (1.44-1.73)

Surname on mailing No name available 1.00

Name not used 2.01 (1.77-2.29)

Name used 1.84 (1.62-2.09)

Respondent selection Any adult 1.00

Next birthday 0.91 (0.81-1.02)

All adults 0.91 (0.81-1.01)

(n) (10,080)

Comparison of RDD telephone and DSF mail survey response rates

State

Response Rates

RDD telephone survey

%(n)

DSF mail survey:All cases

%(n)

DSF mail survey:Cases with 2nd

Mailing(n)

California 39.2(4,318)

31.8(1,266)

39.2(597)

Illinois 38.7(4,462)

36.2(1,356)

42.8(671)

New Jersey 33.8(9,976)

23.2(1,250)

30.5(614)

North Carolina 56.0(7,992)

36.3(1,200)

42.5(602)

Texas 43.6(4,920)

35.5(1,122)

44.4(543)

Washington 45.7(12,910)

39.9(1,334)

44.9(626)

Within household selection

Comparison of “Equalized” Weighted Gender Distributions: %

Female

Population 51.4%

Any Adult 61.5%

Next Birthday 61.5%

All Adults 50.8%

Other demographics of DSF mail survey respondents

Percent some college or more

0

10

20

30

40

50

60

70

80

90

100

% Some college or more

CPS RDD DSF Mail

58.471.8

53.8

Percent white

0

10

20

30

40

50

60

7080

90

100

% White

CPS RDD DSF Mail

67.7 69.564.9

Percent household income > $50,000

010

20

30

4050

6070

8090

100

% Household income > $50,000

CPS RDD DSF Mail

43.848.646.4

Comparison of Survey Estimates

Comparison of Survey Estimates

Health conditions / risk behaviors

Unadjusted prevalence Adjusted odds ratio

Telephone Mail Telephone Mail

Asthma 12.2 14.2 1.00 1.18

Diabetes 8.4 7.6 1.00 0.94

High blood pressure 26.5 27.4 1.00 1.09

Obese (BMI > 30) 29.0 22.4** 1.00 0.83*

Current smoker 18.6 17.0 1.00 1.04

Binge drinking 12.5 20.4*** 1.00 1.77***

Tested for HIV3 42.3 40.5 1.00 0.88

HIV risk behaviors3 4.1 6.9** 1.00 1.74**Significance: * p<.05, ** p<.01, *** p < .001Note: Data weighted for sample design and post-stratified to sex-age totals for each state. Final weights were ratio adjusted to equalize the number of cases across states. Logistic regression models adjusted for state of residence, sex, race, age, education, and having health care coverage.

Reaching cell-only andnon-telephone households

Type of householdtelephone access

1 Based on interviews NHIS conducted July – December, 2004. Source: Stephen J.Blumberg, Julian V. Luke, and Marcie L. Cynamon (2005). “The Prevalence and Impact of Wireless Substitution: Updated Data from the 2004 National Health Interview Survey.” Presented at the 2005 American Association for Public Opinion Research Annual Conference, Miami Beach, FL.

Household telephone access National Health Interview Survey1

(%)

BRFSS mail survey

(%)

Land line 92.1 91.4

-- Landline only --- 13.7

-- Landline and cellular phone --- 79.4

Cellular phone only 5.5 6.0

No telephone 2.4 0.9

Effect of household telephone access on mail survey estimates

Health condition /risk factor

Type of household telephone access

Landline only

Landline and cell phone

Cell phone only

Asthma 1.00 0.84 1.08

Diabetes 1.00 0.86 1.59

High blood pressure 1.00 0.95 0.99

Obese (BMI > 30) 1.00 0.95 1.05

Current smoker 1.00 0.70* 1.06

Binge drinking 1.00 1.56* 1.90*

Tested for HIV 1.00 1.02 1.35

HIV risk behaviors 1.00 1.22 3.95**

Figures are adjusted odds ratios. Significance: * p<.05, ** p<.01, *** p < .001Note: Data weighted for sample design and post-stratified to sex-age totals for each state. Final weights were ratio adjusted to equalize the number of cases across states. Logistic regression models adjusted for state of residence, sex, race, age, education, and having health care coverage.

Advantagesof address-based design

In low response rate states the address-based mail survey approach can yield response rates similar to RDD rates Telephone follow-up of non-respondents should raise

rates

Approach reaches households without land-line telephones

Weighted prevalence estimates were similar for 5 of 8 risk factors

Facilitates geocoding and mapping

Disadvantagesof address-based design

Coverage in rural areas is a potential problem

Mail survey limits number of questions and complexity of survey

Mail survey alone does not yield higher response rates than RDD

Less control over within household selection

Mail survey respondents tend to have higher SES

Next Steps2006 “production level” pilot study in 6 statesTest alternative sampling approaches:

RDD sample reverse-matched for addresses Address-based sample matched for

telephone numbersTest mixed-mode design:

If address available: mail survey with telephone follow-up of nonrespondents

If no address available: telephone survey

Contact:

Michael LinkMLink@cdc.gov

www.cdc.gov/brfss