“…The θ M parameter is defined at a specified ψ value, and ψ values of −0.015 m,−0.1 m,−0.3 m,−0.5 m,−0.6 m,−1 m, and −3.3 m have been used (e.g. Hall et al, 1977;de Witt and McQueen, 1992;Yu et al, 1993;Jarvis et al, 2002;Kutilek, 2004;Deeks et al, 2004;Drewry et al, 2008). In this study, ψ = −0.1 m (Jarvis et al, 2002) was used for reasons which will be elaborated later.…”