Context : A fundamental property determining the transient behaviour of core-collapse supernovae ( CC SNe ) is the amount of radioactive ^ { 56 } Ni synthesised in the explosion .
Using established methods , this is a relatively easy parameter to extract from observations .

Aims : I provide a meta analysis of all published ^ { 56 } Ni masses for CC SNe .

Methods : Collating a total of 258 literature ^ { 56 } Ni masses I compare distributions of the main CC SN types : SNe II ; SNe IIb ; SNe Ib ; SNe Ic ; and SNe IcBL .

Results : Using these published values , I calculate a median ^ { 56 } Ni mass of 0.032 { M } _ { \odot } for SNe II ( N=115 ) , 0.102 { M } _ { \odot } ( N=27 ) for SNe IIb , SNe Ib = 0.163 { M } _ { \odot } ( N=33 ) , SNe Ic = 0.155 { M } _ { \odot } ( N=48 ) , and SNe IcBL = 0.369 { M } _ { \odot } ( N=32 ) .
On average , stripped-enevelope SNe ( SE-SNe : IIb ; Ib ; Ic ; and Ic-BL ) have much higher values than SNe II .
These observed distributions are compared to those predicted from neutrino-driven explosion models .
While the SN II distribution follows model predictions , the SE-SNe have a significant fraction of events with ^ { 56 } Ni masses much higher than predicted .

Conclusions : If the majority of published ^ { 56 } Ni masses are to be believed , these results imply significant differences in the progenitor structures and/or explosion properties between SNe II and SE-SNe .
However , such distinct progenitor and explosion properties are not currently favoured in the literature .
Alternatively , the popular methods used to estimate ^ { 56 } Ni masses for SE-SNe may not be accurate .
Possible issues with these methods are discussed , as are the implications of true ^ { 56 } Ni mass differences on progenitor properties of different CC SNe .