Hi Hassna,

By applying SIFT2 the values of the mean FA in each edges would very small and not interpretable anymore.

I think that perhaps this is a misunderstanding regarding how this calculation is performed.

By using the `-scale_file`

option in `tck2connectome`

, the contribution of each streamline is multiplied by the corresponding factor in this file; if you then additionally use `-stat_edge mean`

, then it will be the *mean* of these values from across those streamlines corresponding to a particular edge that is stored in the connectome matrix.

By additionally providing per-streamline weights via the `-tck_weights_in`

option, then yes, the contribution of each streamline is multiplied by *both* the streamline weight *and* the factor provided via `-scale_file`

; *however*, in the calculation of the per-edge mean, this sum is divided by the *sum of streamline weights* within that edge.

So in this way, the combination of SIFT2 weights and `-stat_edge mean`

act as a *weighted mean*: those values ascribed to streamlines with large weights contribute more to the final result than those ascribed to streamlines with small weights, but the *magnitude* of that weighted mean is still faithful to the magnitudes of those values within the file provided via `-scale_file`

.

Rob