Confounding Bias and Record Keeping of Smoking Status

Record keeping chart…

Invited commentary: confounding, measurement error, and publication bias in studies of passive smoking.

In December 1992, the US Environmental Protection Agency (EPA) declared that environmental tobacco smoke is a class A human carcinogen, responsible for approximately 3,000 lung cancer deaths per year in nonsmokers (1). Although evidence is still accumulating on the role of passive smoking in coronary heart disease among nonsmokers (2, 3), if this association is real, then the total burden of de...

History of Writing and Record Keeping

The ultimate cause of much historical, social and cultural change is the gradual accumulation of human knowledge of the environment. Human beings use the materials in their environment to meet their needs and increased human knowledge of the environment enables human needs to be met in a more efficient manner. The human environment includes the human being itself and the human ability to commun...

BIAS & CONFOUNDING M . Tevfik DORAK

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 ...

Ecological bias, confounding, and effect modification.

Ecological bias is sometimes attributed to confounding by the group variable (ie the variable used to define the ecological groups), or to risk factors associated with the group variable. We show that the group variable need not be a confounder (in the strict epidemiological sense) for ecological bias to occur: effect modification can lead to profound ecological bias, whether or not the group v...