Indiana University

Aging Research


METHODOLOGY FOR THE INDIANA ADVANTAGE INITIATIVE SURVEY

 The AdvantAge Initiative 2008 Community Survey of Adults Aged 60 and Older was conducted in 15 service areas1 and 5 supplemental areas2 in the state of Indiana. A stratified random digit dial (RDD) telephone survey of a representative sample of non-institutional adults aged 60 and older was conducted by International Communications Research (ICR) from February 19, 2008 - May 5, 2008. The average telephone interview time was 30 minutes. Interviews were conducted in English from ICR's telephone centers in Reading, PA and Sharon Hill, PA.

The sample of 15 service areas was stratified into three groups of telephone numbers, (1) those with listed household information indicating the presence of a person aged 60 or older, (2) remaining sample residing in telephone exchanges with a high incidence of households with people aged 60 and older, and (3) all remaining households. This process was completed for each of the 15 service areas. Overall, the sample was RDD since all telephone exchanges in each area were included in the sample. However, higher incidence strata were oversampled to increase the overall survey incidence and reduce survey costs.

The 5 supplemental areas used age-targeted listed sample with additional RDD sample in areas in which listed sample was insufficient.

The total survey sample included 4,969 respondents aged 60 and older (300-302) people in each of the 15 areas; 78-102 people in each of the 5 supplemental areas).

The survey data were weighted to adjust for the varying probabilities of selection. The sample was also weighted by age, gender, and race using Claritas3 data to produce representative results for the non-institutionalized adults aged 60 and older in the 15 Indiana areas and in the 5 supplemental areas.

The margin of error for the sample of 15 areas combined is +/-1.43%. The margin of error for the individual areas is as follows: Areas 1, 3, 4, 5, 6, 9, 10, 11, and 15 (+/-5.66%); Areas 8, 13, and 16 (+/-5.65%); Areas 7, 12, and 14 (+/-5.64%). The margin of error for the supplemental areas is as follows: Gary Midtown NNORC (+/-9.8%), LaSalle Park NNORC (+/-11.2%), Huntington NNORC (+/-11.2%), Linton NNORC (+/-9.8%), and Martindale/Brightwood NNORC (+/-9.7%). In analyses by subgroups the margin of error will be higher.

The overall response rate for this survey was 40.5%4, the cooperation rate, 57.4%.5

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1 There are 16 Area Agencies on Aging located throughout the state of Indiana. Together they cover all counties in the state. This survey excludes Area 2 (Elkhart, Kosciusko, LaPorte, Marshall, and St. Joseph Counties) which was surveyed in 2006.

2 The five supplemental areas are classified as Neighborhood Naturally Occurring Retirement Communities (NNORCs) and the geographic perimeters of these areas were defined by the community representatives using census tracts and block groups in Gary Midtown, Huntington, Linton, LaSalle Park, and Martindale/Brightwood.

3 Claritas is accurate, up-to-date demographic data within any specific geographic market area in the United States, https://www.claritas.com.

4 The AAPOR (American Association of Public Opinion Researchers) response rate formula RR3 was used to calculate the response rate of 40.5% for this study. The formula for RR3 is: I/(I)+(R+NC+O)+e(UH+UO), where I=the number of completed interviews with adults and 60 and older (4,969); R=number of refusals (3,684); NC=non contact (0); O=other (411); UH=unknown eligibility (18,451); UO=unknown other (10,013). The proportion of unknowns estimated to be eligible (e) was 0.113. In short, 4,969/(4,969)+(3,684+0+411)+0.113(18,451+10,013). This formula divides the completes by the sum of the completes, refusals, and a percentage of the households that were not able to be reached. The percentage of households is based on the percentage of households that were successfully interviewed (I+R+NC+O)/(I+R+NC+O+Not eligible).

5 The cooperation rate refers to the percentage of completed interviews out of the number of eligible individuals who were contacted. Using the AAPOR CR3 formula I/(I+R), the cooperation rate was calculated as follows: 4,969/4,969+3,684.

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