This metric is concerned with the minimal distances between pairs of batches.
Usage
avedist(xba, batch)
Arguments
xba
matrix. The covariate matrix, raw or after batch effect adjustment. observations in rows, variables in columns.
batch
factor. Batch variable. Currently has to have levels: '1', '2', '3' and so on.
Value
Value of the metric
Details
For two batches j and j* (see next paragraph for the case with more batches): 1) for each observation in batch j the euclidean
distance to the nearest observation in batch j* is calculated; 2) the roles
of j and j* are switched and 1) is re-performed; 3) the average is taken over all n_j + n_j* minimal distances.
For more than two batches: 1) for all possible pairs of batches: calculate the metric as described above; 2) calculate
the weighted average of the values in 1) with weights proportional to the sum of the sample sizes in the two respective batches.
The variables are standardized before the calculation to make the metric independent of scale.
References
Lazar, C., Meganck, S., Taminau, J., Steenhoff, D., Coletta, A., Molter,C., Weiss-Solís,
D. Y., Duque, R., Bersini, H., Nowé, A. (2012) Batch effect removal methods for
microarray gene expression data integration: a survey. Briefings in Bioinformatics, 14(4), 469-490.
Hornung, R., Boulesteix, A.-L., Causeur, D. (2015) Combining location-and-scale batch effect adjustment with data cleaning by latent factor adjustment. Tech. Rep. 184, Department of Statistics, University of Munich.