Estimation of radiation risk in presence of classical additive and Berkson multiplicative errors in exposure doses

In this paper, the influence of measurement errors in exposure doses in a regression model with binary response is studied. Recently, it has been recognized that uncertainty in exposure dose is characterized by errors of two types: classical additive errors and Berkson multiplicative errors. The combination of classical additive and Berkson multiplicative errors has not been considered in the literature previously. In a simulation study based on data from radio-epidemiological research of thyroid cancer in Ukraine caused by the Chornobyl accident, it is shown that ignoring measurement errors in doses leads to overestimation of background prevalence and underestimation of excess relative risk. In the work, several methods to reduce these biases are proposed. They are new regression calibration, an additive version of efficient SIMEX, and novel corrected score methods.

Multiplicative and Additive Adelson's Snake Illusions

Two different versions of Adelson's snake lightness illusion are quantitatively investigated. In one experiment an additive version of the illusion is investigated by varying the additive component of the atmosphere transfer function (ATF) introduced by Adelson [2000, in The New Cognitive Neuroscience Ed. M Gazzaniga (Cambridge, MA: MIT Press) pp 339–351]. In the other, a multiplicative version of the illusion is examined by varying the multiplicative component of the ATF. In both experiments four observers matched the targets' lightness of the snake patterns with Munsell samples. Increasing the additive or the multiplicative component elicited an approximately equal increase in the magnitude of the lightness illusion. The results show that both components, in the absence of other kinds of information, can be used as heuristics by our visual system to anchor luminance of the object when converting it into lightness.

Is There a Correct Stand Density Index? An Alternate Interpretation

Recent authors have asserted that the original form of Reineke's stand density index is flawed, and that an additive version represents the correct form. An examination of the literature provides no historical or mathematical reason why additivity should be required in the original index. Reineke's stand density index, and the additive or area-based stand density index, should be considered as separate indices with different properties. The sensitivity of the area-based index to stand diameter distribution is illustrated with the Weibull distribution. Its sensitivity provides testable hypotheses that could be used in empirical studies to determine the better index. West. J. Appl. For. 18(3):179–184.