function idx = opt_idx(real_data, pred_list)

	err_list = zeros(size(pred_list, 2), size(real_data, 2));

	for i = 1:size(pred_list, 2)
		err_list(i,:) = sum(abs(real_data - pred_list{i}));
	end

	[min_err, idx] = min(err_list);
end