Measuring theory of planned behaviour concepts with GGP data

The GGS includes four batteries of questions designed to contribute to studies of how people make four key life course decisions: to leave the family home, to form a union, to have a child (or another child), and to retire. Each battery is guided by Icek Ajzen’s social psychological theory of planned behavior (TPB), and allows study of the extent to which the different decisions (measured as intentions) are influenced by people’s attitudes to their going ahead with the decision or behaviour , their perception s of social pressure on them to go ahead or not (subjective norm), and their perceptions of the ease or difficulty with which they would be able to carry out their intention (perceived behavioural control) . The batteries are designed to permit comparison of the relative effects of attitudes, subjective norms, perceived control, and the beliefs that underlie them, across countries and other potentially heterogeneous groups, as well as across the life course decisions themselves. This paper outlines key theoretical and conceptual issues that underpin valid measurement based on the TPB in the context of life course research; provides an overview of different approaches that might be taken to measuring TPB concepts with GGP data (including comparison of measurement at the level of individual beliefs with measurement at the higher conceptual level using techniques that either agglomerate or preserve information about the underlying individual beliefs) depending on the goals of the researcher; and provides examples of country - level comparisons that use each technique in order to illustrate the strengths and limitations of each approach . The paper concludes with some comments on possible improvements to TPB measurement in future waves of the GGS, focusing on measurement of perceived behavioural control