 In analyzing ZT improvements due to lattice thermal conductivity reduction, electrical conductivity, and total thermal conductivity are often used to estimate the electronic component of thermal conductivity, kappa E. The Weidman-Fran's law is widely used to estimate kappa E from sigma measurements. However, significant deviations from the degenerate limit occur for non-degenerate semiconductors where L converges to 1.5 times 10-8WωK-2 for acoustic phonon scattering. A first-order correction to the degenerate limit of L can be based on measured thermal power, independent of temperature or doping. The equation L equals 1.5 plus exp, minus 0.7s, is a satisfactory approximation for L within 5% for single parabolic band-slash acoustic phonon scattering assumption and within 20% for PbC, PbS, PbT, C0.8-0.2 where more complexity is introduced. Using this equation for L rather than a constant value will significantly improve the estimation of lattice thermal conductivity when detailed band structure and scattering mechanism is not known. This article was authored by Hyunsik Kim, Zachary M. Gibbs, Inglutang, and others. We are article.tv, links in the description below.