%0 Journal Article %T The association between correlated colour temperature and scotopic/photopic ratio %A Q Yao %A S Fotios %J Lighting Research & Technology %@ 1477-0938 %D 2019 %R 10.1177/1477153518779637 %X The scotopic/photopic ratio (S/P) is a parameter that may be considered in the design of road lighting. This paper compares the S/P ratio and correlated colour temperature (CCT) for 297 light source spectra identified in IES Technical Memorandum TM-30-15 to test the assumption that higher S/P ratios demand higher CCTs. The results suggest that, for a given lamp type, there is a strong association between S/P ratio and CCT, and hence that for a given CCT only a small variation in S/P ratio is available. However, the results also suggest that a larger variation in S/P ratio is possible if the lighting designer is able to consider a change in lamp type %U https://journals.sagepub.com/doi/full/10.1177/1477153518779637