The individual weighting factors 𝑤𝑤 𝑖𝑖 in the vector 𝒘𝒘 represent the contribution of element i to the target property, here, ionic conductivity. The sign of 𝑤𝑤 𝑖𝑖 is defined by forcing the slope 𝑎𝑎 in Eq. ( ) to be positive, which is equivalent to requiring monotonically increasing proportionality for the element i with positive 𝑤𝑤 𝑖𝑖 and vice versa.