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Statistical risk is a quantification of a situation's risk using statistical methods.These methods can be used to estimate a probability distribution for the outcome of a specific variable, or at least one or more key parameters of that distribution, and from that estimated distribution a risk function can be used to obtain a single non-negative number representing a particular conception of ...
Empirical risk minimization for a classification problem with a 0-1 loss function is known to be an NP-hard problem even for a relatively simple class of functions such as linear classifiers. [5] Nevertheless, it can be solved efficiently when the minimal empirical risk is zero, i.e., data is linearly separable. [citation needed]
In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. [ 1 ] : 38 Due to a lack of harmonization across disciplines, determinant , in its more widely accepted scientific meaning , is often used as a synonym.
where N(t) is the number at risk at the beginning of an interval. A hazard is the probability that a patient fails between t {\displaystyle t} and t + Δ t {\displaystyle t+\Delta t} , given that they have survived up to time t {\displaystyle t} , divided by Δ t {\displaystyle \Delta t} , as Δ t {\displaystyle \Delta t} approaches zero.
The liability-threshold model is frequently employed in medicine and genetics to model risk factors contributing to disease. In a genetic context, the variables are all the genes and different environmental conditions, which protect against or increase the risk of a disease, and the threshold z is the biological limit past which disease develops.
The counterfactual or unobserved risk R A0 corresponds to the risk which would have been observed if these same individuals had been unexposed (i.e. X = 0 for every unit of the population). The true effect of exposure therefore is: R A1 − R A0 (if one is interested in risk differences) or R A1 / R A0 (if one is interested in relative risk).
The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group. Together with risk difference and odds ratio , relative risk measures the association between the exposure and the outcome.
The absolute risk reduction (ARR), however, was much smaller, because the study group did not have a very high rate of cardiovascular events over the study period: 2.67% in the control group, compared to 1.65% in the treatment group. [15] Taking atorvastatin for 3.3 years, therefore, would lead to an ARR of only 1.02% (2.67% minus 1.65%).