How valid are mammography self-reports?

Adolescents' proxy reports of parents' socioeconomic status: How valid are they?

STUDY OBJECTIVE Children's proxy reports on indicators of their parents' socioeconomic status (SES) have either been used uncritically or dismissed as invalid. This paper examines the validity of young adolescents' reports of parental SES by comparing adolescent reports with parents' own reports of SES. DESIGN, SETTING AND PARTICIPANTS In 1990, 924 13 year olds, along with 648 of their father...

Dynamic simulation models: how valid are they?

In a strict sense, the subject of dynamic simulation model validity can be treated thoroughly and quickly: there are no fully valid models because all models are something less than the object, or system, being modeled. For example, millions of people have a conceptual model of the President, but, like fingerprints, no two of these models is exactly the same. Further, none matches precisely eve...

How valid are commercially available medical simulators?

BACKGROUND Since simulators offer important advantages, they are increasingly used in medical education and medical skills training that require physical actions. A wide variety of simulators have become commercially available. It is of high importance that evidence is provided that training on these simulators can actually improve clinical performance on live patients. Therefore, the aim of th...

How many named species are valid?

Estimates of biodiversity in both living and fossil groups depend on raw counts of currently recognized named species, but many of these names eventually will prove to be synonyms or otherwise invalid. This difficult bias can be resolved with a simple "flux ratio" equation that compares historical rates of invalidation and revalidation. Flux ratio analysis of a taxonomic data set of unrivalled ...

Reports of reports: how good are secondary publications in medicine?