From the linked wikipedia article: "female contribution to subsistence does correlate significantly with matrilocal (as opposed to patrilocal) residence in gen

From the linked wikipedia article: "female contribution to subsistence does correlate significantly with matrilocal (as opposed to patrilocal) residence in general; however, this correlation is masked by a general polygyny factor" If you account for polygyny, the more women are involved in creating food the less likely they are to leave. A simple way to look at it is that parents invest time to teach one gender to support them at old age. If you invest time and energy to teach your sons the local methods to create food then you want them to stick around. If you invested same amount of time to teach local knowledge on both and one left then not only have you wasted half the time and effort but that local knowledge might not even be useful for the party that left. polygyny add an other layer on it as an increase in the female contribution to subsistence also increase the the probability for polygyny which in turn increase the probability for patrilocality. A bit of cynicism would explain this by saying that if women account for the majority of creating food then fewer men is needed, resulting in polygyny, which create an power imbalance as those men will be a blood relative to a significant larger number of children compared to any woman. To apply this then to vikings, if the men left to pillage then it must have been the women that worked the land and raised animals, which mean the they likely invested the time to teach their daughters to do the same and relied on them for support at old age.