mlen(data, coords, loc.id, direction, mle = "avg")which_lines."trm", the trimmed arithmetic average will be used to calculate the mean lengths. If "mdn", the trimmed median will be considered. If "mlk", the maximum likelihood mean lengths will be computed. If "avg", the arithmetic mean will be performed. For backward compatibility reasons, it can accept logical values, so that TRUE is equivalent to "mlk" and FALSE to "avg".If the stratum lengths are censored, the maximum likelihood approach is more appropriate than the arithmetic mean. In this case, the stratum lengths are assumed to be independent realizations from a log-normal random variable. The quantity to maximize is $$L(\mu_1, \ldots, \mu_K, \sigma_1, \ldots, \sigma_K) = \prod_{i = 1}^m \prod_{k = 1}^K \left[ \int_{l_i}^{l_i+u_i} \frac{1}{x \sigma_k \sqrt{2}} \exp \left\lbrace - \frac{(\log x - \mu_k)^2}{2 \sigma_k^2} \right\rbrace \right]^{z_{k, i}} \mbox{d}x,$$ where $mu$ and $sigma$ are vectors of parameters, $l_i$ is the observed stratum length, $u_i$ denotes the upper bound of the censor and $z_k$ denotes a dummy variable which assumes value 1 if and only if the $i$-th stratum is referred to the $k$-th category.
Sartore, L. (2010) Geostatistical models for 3-D data. M.Phil. thesis, Ca' Foscari University of Venice.
which_lines