avedist {bapred} R Documentation

## Average minimal distance between batches

### Description

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.

### 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.

### Value

Value of the metric

### Note

The smaller the values of this metric, the better.

Roman Hornung

### 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. (2016) Combining location-and-scale batch effect adjustment with data cleaning by latent factor adjustment. BMC Bioinformatics 17:27.

### Examples

```data(autism)

avedist(xba=X, batch=batch)
```

[Package bapred version 1.0 Index]