Neural Networks for Survival Prediction in Medicine Using Prognostic Factors: A Review and Critical Appraisal

Table 1

Notations used in this review.

Notation	Description
	Survival time
	Maximum follow-up time (in years)
	Conditional survival probability in (output) unit
	Conditional event probability in (output) unit , with
	Output unit
	Connection weight matrix
	Vector of regression coefficients
	Covariate matrix
	Vector of covariates for individual
	Observed outcome of individual in unit
	Activation function for the hidden layer
	Activation function for the output layer
	Bias unit (node)
	Error (loss) function for the ANN
	Event indicator of individual for time interval
	Probability that patient relapses in time period (interval)
	Cumulative event probability in (output) unit