chi multiples
 N    ID    z   Narcs   chip    chix    chiy    chia  rmss  rmsi
 0     2c 1.000   3      0.13    0.00    0.00    0.00  0.01  0.03
 1     3d 2.000   4      0.11    0.00    0.00    0.00  0.01  0.04
chimul                   0.25    0.00    0.00    0.00  0.01  0.04

chitot 0.25