Multiscaled randomness: A possible source of 1/fnoise in biology

We evaluate the possibility that the 1/f fluctuations observed in many biological time series result simply from the fact that biological processes have many inputs with differing time scales. We present a stochastic model whose output is the summation of multiple random inputs (i.e., different regulatory mechanisms). We derive the conditions under which the model reproduces the complex fluctuations and 1/f scaling observed in biological systems. Simulations demonstrate that if model parameters are unconstrained, the likelihood of generating 1/f noise is quite small. Thus, while the model can be used to generate 1/${\mathit{f}}^{\mathrm{\beta }}$ noise with various scaling exponents, it is unlikely that the 1/f behavior observed in many biological systems is due only to the fact that these systems are regulated by many different inputs acting on different time scales. © 1996 The American Physical Society.