 				getSquareSum,
 				getVariance,
 				getStandardDeviation,
-				getRunningTotals
+				getRunningTotals,
+				validateCache
 			];
 			for each (var func:Function in functions)
 				cache[func] = new Dictionary(true);

			if (column == null)
				return NaN;

			if (detectLinkableObjectChange(cache, column))
			{
				var min:Number = NaN;
				var max:Number = NaN;

				cache[getMean][column] = mean;
				cache[getVariance][column] = variance;
				cache[getStandardDeviation][column] = standardDeviation;
				cache[getRunningTotals][column] = runningTotals;
				// remember the trigger counter so we can detect when the cache becomes invalid
				cache[validateCache][column] = column.triggerCounter;
			}
			
			return cache[statsFunction][column];
