  The main goal of this work is to explore which elements carry the most
information about the birth origin of stars and as such that are best suited
for chemical tagging. We explored different techniques to minimize the effect
of outlier value lines in the abundances by using Ni abundances derived for
1111 FGK type stars.We evaluated how the limited number of spectral lines can
affect the final chemical abundance. Then we were able to make an efficient
even footing comparison of the [X/Fe] scatter between the elements that have
different number of observable spectral lines in the studied spectra. We found
that the most efficient way of calculating the average abundance of elements
when several spectral lines are available is to use a weighted mean (WM) where
as a weight we considered the distance from the median abundance. This method
can be effectively used without removing suspected outlier lines.We showed that
when the same number of lines is used to determine chemical abundances, the
[X/Fe] star-to-star scatter for iron group and $\alpha$-capture elements is
almost the same. On top of this, but at a lower level the largest scatter was
observed for Al and the smallest for Cr and Ni. We recommend caution when
comparing [X/Fe] scatters among elements that have a different number of
spectral lines available. A meaningful comparison is necessary to identify
elements that show the largest intrinsic scatter and can be thus used for
chemical tagging.
