A method of assessing the quality of reconstructing signals from finite sets of samples is presented. The assessment uses a sensitivity function that provides information about the reliability of the reconstructed signal at every time instant. The sensitivity function equals zero where the reconstruction is perfect (sampling instants) and achieve global maximum where the available samples do not provide any information about the original signal (typically at /spl plusmn//spl prop/). The proposed method measures the quality of reconstructing before the actual samples of the signal are taken.