Distributions of individual (A) stopping angle θ₁ and (B) starting angle θ for five types of beads of d = 5/6 mm. (C) Normalized distribution of ε₁ for θ₁ (or ε₂ for θ₂). Curve indicates the normal distribution. (D) Conditional average of θ₁ - θ_r and (E) δθ - Δθ as functions of the preceding θ₂ - θ_m. Straight lines in (D) and (E) indicate y = -0.4x and y = 1.4x, respectively. (F) Standard deviations of P(δθ), P(θ₁), and P(θ₂) as functions of Δθ. Solid points refer to the results of glass beads of d = 2 mm.