Pre-ICU status was, however, retrospectively evaluated at phone interview with a potential bias in case of functional status underestimation.
Finally, any causal inference study based on observational data could be biased in case of missing confounding variables.
Clearly, their behavior is strongly biased in case of the small regularization parameter, while they perform similarly in case of a proper regularization.
This latter derives SV from pulse contour analysis of arterial femoral pressure, a derivation which could be biased in case of IAH and vascular constraint [ 12].
The non-response analysis performed during study is sensitive to selection bias in case of low response rates and selective responders.
This could mean a potential limited bias in case of the premature unblinding of a patient, as the investigators might draw conclusions concerning the treatment of the remaining patients at their centers.
However, diaries always suffer from approximation and although participants were instructed to fill in their diary continuously, we could not control for recall bias in case of non-compliance.
Knox's method is known to be subject to possible bias in case of nonuniform population shifts over the time period (Besag and Newell, 1991; Kulldorff and Hjalmars, 1999) and the probability to detect space time clustering due to population shifts increases with the number of close pairs observed (Kulldorff and Hjalmars, 1999).
We would not expect such strong bias in case of AMI, but for other less acute CVD's there might be a tendency that immigrants more often go to the hospital directly, even if they are expected to be treated or referred by their general practitioner.
In the simulation study, the prediction errors improved with respect to the variance and bias terms in case of larger training data set sizes.
