The scattered intensity can be plotted as a function of the angle to give information on the R which can simply be calculated using the Guinier approximation as follows:
where ln(ΔR(θ)) = lnP(θ) also known as the form factor with q = 4πnsin(θ/2)/λ. Hence a plot of the corrected Rayleigh ratio, ΔR(θ) vs sin(θ/2) or q will yield a slope R/3. However, this approximation is only true for qR < 1. Note that for a Guinier plot, the value of dn/dc and the concentration is not needed.