The explanation of why the stability of an alkene increases with the degree of alkyl substitution is a matter of some conjecpt of hypercon ju gation. According to iupac, in the formalism that separates bonds into Q and TT types, hyerconjugation is the interaction of Q bonds(e.g.,C-H,C-C,,etc) with a TT network. Other explanations are based on the interactions of filled and empty molecular orbitals and call into question the appropriatenessof using hyperconjugation as an explanation. Even in the absence of an explanation, the experimental facts are unambiguous: the stability of an alkene increases with the number of alkyl groups on the carbon atoms of the double bond.