Calculation of estimated biological variation
Genes that have been normalized by Normalize Single Cell Data have an expected variance of
We define the `estimated biological variation'
in a normalized sample to be the fraction of the total variance that is above the expected variance due to random noise for each gene

Here, are the normalized expressions of gene
. Note that this estimate assumes that all variation remaining after normalization is of `biological' origin. This is unlikely in practice, and the estimate will often be too high.