I was curious if anyone could help me with something. I got into a discussion with my older sister about a so called "second shift" phenomenon which has the claim that women end up working more hours in non-paid work around the house then men and that out weighs any additional hours of paid work that men do.

Being the scientist and engineer that I am, I went looking for data that either supports or refutes the claim and all I can find are averages without reported n values or standard deviations and the averages are unconvincingly different. Do y'all know of a credible and preferably per reviewed bit of literature that supports or refutes this claim and includes appropriate data to support their conclusions?