...........................................................................................1 LIST OF ABBREVIATIONS .....................................................................2 ORIGINAL ARTICLES.............................................................................3 PROLOGUE ...........................................................................................4 BACKGROUND......

The paper provides a first survey of the literature on external validity, using as a starting point recent debates regarding the use of randomized evaluations to inform policy. Besides synthesising contributions to the programme evaluation literature we consider definitions of external validity from other sub-disciplines within economics, such as experimental economics and the time-series forec...

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...

3.1 HUMAN AGENCY: CLAIMING CAUSATION THROUGH INTERVENTION 15 3.1.1 CRITIQUE #1: LACK OF EXTERNAL VALIDITY (ACCIDENTALITY) 16 3.1.2 CRITIQUE #2: THREATS TO INTERNAL VALIDITY 16 3.1.3 CRITIQUE #3: PRE-EMPTION 17 3.2 GENERATIVE CAUSATION: THE DESCRIPTION OF THE CAUSAL MECHANISM 18 3.2.1 HOW CAUSATION IS CLAIMED: DIGGING DEEP 20 3.2.2 QUALITY OF INFERENCE 21 3.2.3 MECHANISMS HAVE PARTS: COMPONENT C...

1. Background In the UK, the NIHR vision sees ‘more patients and health professionals participating in health research’ [1]. Fundamental to health research is the testing of interventions through RCTs. Achieving high participation in RCTs has traditionally been difficult. Published data show that a minority of RCTs recruit successfully [2,3]. Recruitment problems reduce the total recruited samp...

Introduction Randomised Controlled Trials (RCTs) produce relative treatment effects that have high internal validity. However they may suffer from lack of external validity when used as inputs to cost-effectiveness analyses (CEA). If differences in RCT and CEA populations can be described by a set of observed covariates, then it is possible to adjust for these differences. A common approach is ...

Much of the methodological discussion around experiments in economics and other social sciences is framed in terms of the notions of internal and external validity. The standard view is that internal validity and external validity stand in a relationship best described as a trade-off. However, it is also commonly held that internal validity is a prerequisite to external validity. This article a...

CONTEXT The transition to retirement has been recognized as a turning point in determining physical activity and may present a critical "window" for promoting physical activity. This systematic review examined changes in physical activity across the retirement transition, whether these changes vary by SES, and what is known about predictors of these changes. EVIDENCE ACQUISITION Peer-reviewed...

Randomized controlled trials (RCTs) are routinely used in medicine and are becoming more popular in economics. Data from RCTs are used to learn about treatment effects of interest. This paper studies what one can learn about the average treatment response (ATR) and average treatment effect (ATE) from RCT data under various assumptions and compares that to using observational data. We find that ...