where dist(xi;xj) denotes the Euclidean distance between
genes xi and xj, and xip is the pth experiment of gene xi.
The second step involves the prediction of the missing value
using the observed values belonging to the selected group of
genes. At this stage, an average of values in experiment i from
the k closest genes is then used as an estimate for the missing
value in gene xg. The estimated value ˜ xgi of the missing xgi
can be calculated by: