6.7 Let X1,...,Xm and Y1,...,Yn be independently distributed according to N(,2) and N(, 2), respectively. Find

6.7 Let X1,...,Xm and Y1,...,Yn be independently distributed according to N(ξ,σ2)

and N(η, τ 2), respectively. Find the minimal sufficient statistics for these cases:

(a) ξ , η, σ, τ are arbitrary: −∞ < ξ , η < ∞, 0 <σ, τ .

(b) σ = τ and ξ , η, σ are arbitrary.

(c) ξ = η and ξ , σ, τ are arbitrary.