Commercial truck driver Hours-of-Service (HOS) rules are periodically revised to reduce driver fatigue and improve driver health in costefficient ways. HOS research must demonstrate causal relationships between HOS parameters and important safety outcomes. Thus, two scientific requirements are internal validity (demonstration of true cause-effect relationships) and external validity (generaliza...

Readers of medical literature need to consider two types of validity, Internal and extemal. Internal validity means that the study measured what it set out to; external validity Is the ability to generalise from the study to the reader's patients. With respect to internal validity, selection bias, information bias, and confounding are present to some degree in all observational research. Select...

This article is a continuation of the previous module on designing questionnaires and clinical record form in which we have discussed some basic points about designing the questionnaire and clinical record forms. In this section, we will discuss the reliability and validity of questionnaires. The different types of validity are face validity, content validity, criterion validity, and construct ...

In two large web-based studies, across five distinct criteria, presenting survey items one-at-a-time was psychometrically either the same or better than presenting survey items all-at-once on a single web page to volunteer participants. In the one-at-a-time format, participants were no more likely to drop-out of the study (Criterion 1), and were much more likely to provide answers for the surve...

Bandura’s social cognitive construct “perceived selfefficacy” has been used widely to understand individual behavior as a function of domain-specific beliefs about personal capacities. Collective efficacy is the extension of the self-efficacy construct to organizations and groups; it refers to beliefs about collective capacities in specific domains. Our research is investigating the use of coll...

Shared leadership is viewed as an effective management form to encounter increased complexity in modern work life. However, the lack of reliable and valid instruments to assess shared leadership behaviors has limited empirical research. Based on literature in leadership and team work research a questionnaire was developed to assess four different aspects of shared leadership behavior—task-, rel...

A great deal of developmental research has relied on self-reports solicited using the "some/other" question format ("Some students think that… but other students think that…"). This article reports tests of the assumptions underlying its use: that it conveys to adolescents that socially undesirable attitudes, beliefs, or behaviors are not uncommon and legitimizes reporting them, yielding more v...

Introduction In epidemiologic research, it is essential to avoid bias, to control confounding and to undertake accurate replication. Bias, confounding and random variation/chance are the non-causal reasons for an association between an exposure and outcome. These major threats to internal validity of a study should always be considered as alternative explanations in the interpretation. Bias is ...

Institutions are governance tools. They are useful only if they impact on behaviour: of citizens, and of those administering the legal system. Models of behaviour are therefore crucial for institutional analysis and design. In light of this, this paper draws lessons for institutional analysis and design resulting from the models of multi-attribute decision-making assembled in this special issue...