Fig 5.

(i) Nominal level of heterogeneity tests Ψ₁ and Ψ₂; (ii) - (iv) Power of heterogeneity tests Ψ₁ and Ψ₂ when Δ= 0.5, 1.0, 1.5. In the above figures, dashed lines represent Ψ₁, which is constructed based on $\check{\beta }$ , and solid lines represent Ψ₂, which is constructed based on $\widehat{\beta }$ .