public synchronized Pair<List<S>, Long> getStdParams() {
        List<S> l = new ArrayList<>(2);
        l.add(sumVal);
        l.add(sumSqVal);
        Pair<List<S>, Long> p = new Pair<>(l, rowCountVal);
        return p;
      }
It computes a global standard deviation for a given column and its value. Standard deviation is
square root of (average of squares - average*average). From individual regions, it obtains sum,
square sum and number of rows. With these, the above values are computed to get the global std.
@param table table to scan.
@param scan  the HBase scan object to use to read data from HBase
@return standard deviations
@throws Throwable The caller is supposed to handle the exception as they are thrown &amp;
                  propagated to it.
hbase-endpoint/src/main/java/org/apache/hadoop/hbase/client/coprocessor/AggregationClient.java