 The distribution of the observed distances is used to estimate a "detection function" that describes the probability of detecting an object at a given distance.Given that various basic assumptions hold, this function allows the estimation of the average probability "P" of detecting an object given that is within width "w" of the line.Object density can then be estimated as , where "n" is the number of objects detected and "a" is the size of the region covered (total length of the transect ("L") multiplied by 2"w").