Search results
Results from the WOW.Com Content Network
In survival analysis, the hazard ratio (HR) is the ratio of the hazard rates corresponding to the conditions characterised by two distinct levels of a treatment variable of interest. For example, in a clinical study of a drug, the treated population may die at twice the rate of the control population.
The hazard ratio is the quantity (), which is = in the above example. From the last calculation above, an interpretation of this is as the ratio of hazards between two "subjects" that have their variables differ by one unit: if P i = P j + 1 {\displaystyle P_{i}=P_{j}+1} , then exp ( β 1 ( P i − P j ) = exp ( β 1 ( 1 ...
This approach performs well for certain measures and can approximate arbitrary hazard functions relatively well, while not imposing stringent computational requirements. [5] When the covariates are omitted from the analysis, the maximum likelihood boils down to the Kaplan-Meier estimator of the survivor function.
In two-sector macroeconomic models, the Harrod–Johnson diagram, occasionally referred to as the Samuelson-Harrod-Johnson diagram, is a way of visualizing the relationship between the output price ratios, the input price ratios, and the endowment ratio of the two goods. [1] [2] Often the goods are a consumption and investment good, and this ...
The Bass diffusion model is derived by assuming that the hazard rate for the uptake of a product or service may be defined as: = () = + [()] where () is the probability density function and () = is the survival function, with () being the cumulative distribution function.
A hazard quotient is the ratio of the potential exposure to a substance and the level at which no adverse effects are expected. If the Hazard Quotient is calculated to be less than 1, then no adverse health effects are expected as a result of exposure. If the Hazard Quotient is greater than 1, then adverse health effects are possible.
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.
In full generality, the accelerated failure time model can be specified as [2] (|) = ()where denotes the joint effect of covariates, typically = ([+ +]). (Specifying the regression coefficients with a negative sign implies that high values of the covariates increase the survival time, but this is merely a sign convention; without a negative sign, they increase the hazard.)