public static void cleanDataSet() {
		// Remove users that have the same rating for each item OR that have
		// less than 10 ratings
		ArrayList<Integer> usersToRemove = new ArrayList<Integer>();
		for (Integer userID : userItemRatings.keySet()) {
			if (findMinimum(userItemRatings.get(userID).values()) == findMaximum(userItemRatings
					.get(userID).values())) {
				usersToRemove.add(userID);
			} else if (userItemRatings.get(userID).size() < 10) {
				usersToRemove.add(userID);
			}
		}

		for (Integer userID : usersToRemove) {
			userItemRatings.remove(userID);
		}

	}