Olink uses intensity normalization, with the median as the normalization factor, when samples are randomized across plates and projects. The intensity normalization adjusts the data so that the median value for an assay on each plate is equal to the overall median across all plates. This method assumes that the actual median of each plate is the same. The way to ensure this is to randomize the samples beforehand. If complete randomization can be assumed, this is a robust and high performing normalization method. Intensity normalization is performed in the following way:
- For each assay, calculate the overall median value for all samples and plates.
- For each plate and assay, calculate the plate specific median value.
- For each assay, subtract the plate specific median from every value for the plates (equals centralizing to median 0).
- For each assay, add the overall median value (equals centralizing to the overall median).
See the related FAQ:
For more information see our white paper, “Data normalization and standardization“.