double mostCommonValue(int col) {
		TreeMap<Double, Integer> tm = new TreeMap<Double, Integer>();
		for(int i = 0; i < rows(); i++) {
			double v = get(i, col);
			if(v != MISSING)
			{
				Integer count = tm.get(v);
				if(count == null)
					tm.put(v, new Integer(1));
				else
					tm.put(v, new Integer(count.intValue() + 1));
			}
		}
		int maxCount = 0;
		double val = MISSING;
		Iterator< Entry<Double, Integer> > it = tm.entrySet().iterator();
		while(it.hasNext())
		{
			Entry<Double, Integer> e = it.next();
			if(e.getValue() > maxCount)
			{
				maxCount = e.getValue();
				val = e.getKey();
			}
		}
		return val;
	}