&gt; It&#x27;s very unlikely that there exists a treatment where all the effect is on a 35-variable interaction and none of the effect is visible when looking at each variable singly.<p>Maybe something about genetic modifications where 35 different point modifications to the genome have to happen in order to allow synthesis of a working protein?  If you measured the effect of each point modification, you might measure it as zero.<p>I&#x27;m analogizing from trying to do statistical tests of whether a password is correct.  At least in systems that aren&#x27;t vulnerable to timing attacks, you can&#x27;t just test part of the password and see if you get a little bit more access to the system as a result. :-)