Doppler sonography of 29 extracranial carotid arteries was performed twice within three days or less. Angiography revealed stenoses with from 10 to 95% diameter reduction in 25 internal carotid arteries whereas four vessels were found to be normal. The systolic peak frequency of the internal carotid artery read from the Doppler spectrum (n = 29) could be reproduced very well. This was shown by ...

In epidemiological studies using linear regression, it is often necessary for reasons of economy or unavailability of data to use as the independent variable not the variable ideally demanded by the hypothesis under study but some convenient practical approximation to it. We show that if the correlation coefficient between the "practical" and "ideal" variables can be obtained, then a range of u...

The Dantzig selector performs variable selection and model fitting in linear regression. It uses an L1 penalty to shrink the regression coefficients towards zero, in a similar fashion to the Lasso. While both the Lasso and Dantzig selector potentially do a good job of selecting the correct variables, they tend to over-shrink the final coefficients. This results in an unfortunate trade-off. One ...