  I re-examine a recent work by G. Landi and G. E. Landi. [arXiv:1808.06708
[physics.ins-det]], in which the authors claim that the resolution of a tracker
ca vary linearly with the number of detection layers, $N$, that is, faster than
the commonly known $\sqrt{N}$ variation, for a tracker of fixed length, in case
the precision of the position measurement is allowed to vary from layer to
layer, i.e. heteroscedasticity, and an appropriate analysis method, a weighted
least squares fit, is used.
