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leo. - Level-One Study (Level One)

Research Question

The Level One Study is analyzing the level of functional illiteracy.

Topics: Learning at an adult age. Occupational status. Characteristics of main professional occupation. Participation in regular education (Part 1: school, part 2: professional training). Educational background. Use of information and communication technology. Language skills. Current life situation and coping with life problem.

leo. was conducted once parallel to the cross-section Adult Education Survey (AES) in 2010. No repetition of this addition is planned.
With first results published in 2011 the project offered important impulses for political decision-makers and practitioners, and helped to raise public awareness for alphabetization as a topic.

Test Language


Test Period

02.03.2010 - 27.07.2010

Test Area


Population / Sample

leo-AES: individuals in private households aged between 18 and 64

leo-additional survey: individuals in private households aged between 18 and 64, who hold degrees similar to a Certificate of Secondary Education, have a lower educational level, or hold no educational degree

The net sample comprises 7.035 individuals, complemented with an additional sample of 1.401 individuals from the lower educational stratum. The selection of individuals for the AES questions was done using a multistage, three level random sample (ADM standard). For the additional sample individuals were randomly chosen from the TNS Infratest panelist pool. These individuals hold degrees similar to a Certificate of Secondary Education, participated in omnibus surveys between 2008 and 2010, and were willing to participate in another survey.

Sample Size

8,436 interviewees

Survey Procedure and Instruments

Computer Assisted Personal Interview (CAPI)

Link to the Detailed Description of the Study

leo. - Level-One Study (Level One) – study description
Projektwebseite Universität Hamburg (link) (in German)
Projektinformationen beim Erhebungsinstitut TNS Infratest (link) (in German)

Persistent Identifier

DOI: 10.4232/1.11913

Data Accessible via Research Data Centre

GESIS - Leibniz-Institute for the Social Sciences

Information about the user conditions can be found here:

Documentation of Variables

The study was deposited at GESIS with detailed methodological information. All relevant documents can be found in the study description.


GESIS Team Datenservice
Phone: +49 221 / 476 94 - 420
Email: datenservice.das[at]

Selection of Publications using the Data

Grotlueschen et al. (2014) Stereotypes versus Research Results Regarding Functionally Illiterate Adults. Conclusions from the First German Level-One Survey and the Learner Panel Study. Leo. – News, 1.
Other publications at sowiport (GESIS, German only)

Related Data

Adult Education Survey (AES) 2010

Research Area(s)