The temperature-dependent part of the electrical resistivity ρ(T) of a metal consists of the sum of two terms, one term being due to electron–phonon scattering ρcp(T) and the other term being due to electron–electron scattering ρcc(T). One may write[Formula: see text]where θD, is the Debye temperature of the metal and the coefficients C and A give the magnitudes of ρcp(T) and ρcc(T), respectively. For a metal whose electrical resistivity exhibits "simple" behavior, it had been expected that the measured data for ρ(T) would have the following properties. (i) The function f(T/θD) should approach (T/θD) for [Formula: see text]. (ii) The magnitude of the coefficient C should be the same, or nearly so, for all measured samples. (iii) The magnitude of the coefficient A should be the same, or nearly so, for all measured samples.The low-temperature ρexpt(T) data for potassium, which has by now been measured for many samples, exhibit none of these three properties. A discussion will be presented of the reasons for this "non-simple" behavior of ρexpt(T) for potassium.