ðɪs hjuːɹˈɪstɪk fˈaɪndz mˌæθɪmˈæɾɪkəl səpˈoːɹt æz ɐ kˈɑːmpɹəmˌaɪz bᵻtwˌiːn tˈuː mˈɛθədz ʌv ɛkspɹˈɛsɪŋ ðə kəmbˈaɪnd ɪfˈɛkts əvə wˈeɪvz ˈævɹɪdʒ ˈʌpwɚd ænd ˈævɹɪdʒ dˈaʊnwɚd dˌiːvɪˈeɪʃənz fɹʌm mˈiːn sˈiː lˈɛvəl, nˈeɪmli ɐ ðə sˈʌm ʌvðɪ ˈæbsəlˌuːt vˈæljuː əvə sˈaɪn wˈeɪvz ˈævɹɪdʒ mˈiːn dˌiːvɪˈeɪʃən dˈʊɹɹɪŋ ɪts ˈʌpwɚd hˈæfsˈaɪkəl ænd ðɪ ˈæbsəlˌuːt vˈæljuː ʌv ðæt mˈiːn dˌiːvɪˈeɪʃən dˈʊɹɹɪŋ ɪts dˈaʊnwɚd hˈæfsˈaɪkəl zˈiəɹoʊ.sˈɪkshˈʌndɹɪd θˈɜːɾi sˈɛvən plˈʌs zˈiəɹoʊ.sˈɪkshˈʌndɹɪd θˈɜːɾi sˈɛvən
This heuristic finds mathematical support as a compromise between two methods of expressing the combined effects of a wave's average upward and average downward deviations from mean sea level, namely a) the sum of the absolute value of a sine wave's average (mean) deviation during its upward half-cycle and the absolute value of that mean deviation during its downward half-cycle (|0.637| + |-0.637|