Erratum to: Proportionality between variances in gene expression induced by noise and mutation: consequence of evolutionary robustness
© Kaneko; licensee BioMed Central Ltd. 2012
Received: 24 May 2012
Accepted: 3 December 2012
Published: 9 December 2012
Although the simulation data as well as the conclusion on the proportionality between V ip (i) and V g (i) in the work  is correct, interpretation of some data therein should be corrected. As the sampling number (L = 200) to measure the average gene expression level is not large enough, there is a bias in the estimate in V g (i). Finiteness in the number of sampling L will generally cause a bias of the order of V ip (i)/L, in the estimate of the variance V g (i). The too good proportionality between V ip (i) and V g (i) for large σ, shown in Figure two (a)(b) of  (especially for small V g (i)), is due to this artifact. Accordingly, the sharp peak at ∼1/L = 1/200 in Figure three of  is due to this insufficiency by the sample number.
To sum up, the main claim of , i.e., proportionality between V ip (i) and V g (i) is valid, but the value of the proportion coefficient ρ = V g (i)/V ip (i) should be corrected. It decreases with the noise level, in contrast to the discussion in  for large σ. Major factor on this proportionality is attributed to the correlation of each variance with the average value : In other words, a state with an intermediate expression level (i.e., smaller ) can be more easily switched on or off, both by noise and also by mutation, and hence the variances generally increase as approaches 0. Still, some correlation between V ip (i) and V g (i) remains even after removing this correlation through .
I regret any inconvenience that misintepretation of the data with an insufficient sample size may have caused.
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