SAM Algorithm
The data is
, i = 1, 2, ... p genes, j = 1, 2, ... n samples, and response data
, j = 1,2, ... n (
may be a vector).
Generic SAM procedure :
- Compute a statistic : ; i = 1, 2, ... p
- is a score.
- is a standard deviation.
- is a fudge factor.
Details of and for Two Class, Unpaired Data response type :
-
- .
- .
-
- ; k = 1,2. = 1 or 2.
- is the number of observations in .
Computation of :
- Compute the 100 quantiles of the values, denoted by .
- For (0, .01, .02, ... 1.0)
- Let , where be the percentile of the values.
- Compute , j = 1, 2, ... 100, where _mad_ is the median absolute deviation from the median, multiplied with 1.4826.
- Compute cv() = .
- Choose = argmin[cv()].
- Finally compute = . is henceforth fixed at the value .