Since its beginnings in 2003, the American Life Panel has expanded from about 500 to over 5,000 U.S. households. ALP members have been recruited from multiple sources over the years. Many ALP members were recruited from other completed surveys. The original ALP cohort, for example, was initially recruited for a RAND-University of Michigan collaboration on the Health and Retirement Survey. Since then, ALP members have been recruited from several other surveys and directly for the panel using multiple modes (in-person/face-to-face, telephone, and mail) and probability-based sampling methods, including address-based samples and telephone (random-digit dial) samples.
The ALP also includes a smaller number of members recruited through non-probability methods. These members are primarily used for pilot-testing, experiments, or other studies not intended for analysis with inferential statistics. Non-probability methods of ALP recruitment include snowball sampling, respondent driven sampling (RDS), and additional household member recruitment.
A consistent feature of ALP recruitment is to provide the technological means for recruits to access and complete online surveys. This is an important feature to ensure the ALP is representative of all adults, not just those with internet access. In the early days of the ALP, Web-TVs were provided, while today Chromebooks and hotspots are provided. Increasingly, ALP members complete surveys on their smartphones.
Additional information on ALP member recruitment is available in the ALP Methodology Report.
ALP data files include a recruit_type variable that indicates the origin of each panel member. Values for this variable are:
- "ALP mailout" — mailing experiment
- "ORC_Phase1" — random digit dials
- "Added member" — referred by original member
- "ALP_coldcall" — phone experiment
- "ALP_hispanic_recruitment" — primarily RDS
- "ALP_intergenerational_recruitment" — relatives referred by ALP members
- "Michigan" — MS Internet
- "Snowball" — Snowball
- "SRG" — MS CATI
- "Stanford" — National Survey Project
- "Vulnerable_pop" — Vulnerable Population
The ALP has invited other (adult) household members of the sampled panel members to join, thus allowing intra-household comparisons. These panel members have a numeric identifier ending in a value greater than 1 (e.g. identifier 10017494:2). At present, approximately 17 percent of surveyed households have more than one panel member. As a result, the ALP cannot be used as a proper household-survey panel and should be considered primarily a panel of individuals. All individual respondents are assigned a household recruitment type variable, which indicates the sample origin of the sampled household member (i.e., invited household members receive the recruitment_type value of the original sample member). Some member-referred respondents have since left the origin household and established separate households. Values for the recruitment_type variable are:
- 0 MS Internet
- 1 MS CATI
- 2 Snowball
- 3 National Survey Project
- 6 Mailing Experiment
- 7 Phone Experiment
- 8 Vulnerable Population
- 9 Respondent Driven Sampling
- 10 ALP Intergenerational
- 11 ORC
To identify ALP members recruited by nonprobability-based methods, researchers should combine recruit_type "Added_member" and "ALP_intergenerational_recruitment" with recruitment_type values 2, 6, 7, 9, and 10.