Parameter: λ₁₃

Parameter: λ₂₄ Identified

Algebraic Equations:

σ₂₃²λ₂₄-σ₂₂σ₃₃λ₂₄+σ₂₄σ₃₃-σ₂₃σ₃₄,
σ₁₃σ₂₃λ₂₄+σ₁₄σ₃₃-σ₁₃σ₃₄,
σ₁₃σ₂₂λ₂₄+σ₁₄σ₂₃-σ₁₃σ₂₄

Single Door Criterion:

{2} ⊥ {4} | {3}
{2} ⊥ {4} | {1,3}

Instrumental Variable:

1 | {3}

Parameter: λ₃₄ Identified

Algebraic Equations:

σ₁₃λ₃₄-σ₁₄,
σ₂₃²λ₃₄-σ₂₃σ₂₄-σ₂₂σ₃₃λ₃₄+σ₂₂σ₃₄

Single Door Criterion:

{3} ⊥ {4} | {2}
{3} ⊥ {4} | {1,2}

Instrumental Variable:

1 | {}
1 | {2}

Parameter: ω₁₁ Identified

Algebraic Equations:

-σ₁₁+ω₁₁

Parameter: ω₁₃

Parameter: ω₂₂ Identified

Algebraic Equations:

-σ₂₂+ω₂₂

Parameter: ω₂₃ Identified

Algebraic Equations:

-σ₂₃+ω₂₃

Parameter: ω₃₃

Parameter: ω₄₄ Identified

Algebraic Equations:

-σ₂₄²σ₃₃+2σ₂₃σ₂₄σ₃₄-σ₂₂σ₃₄²-σ₂₃²σ₄₄+σ₂₂σ₃₃σ₄₄+σ₂₃²ω₄₄-σ₂₂σ₃₃ω₄₄,
-σ₁₄σ₂₄σ₃₃+σ₁₄σ₂₃σ₃₄+σ₁₃σ₂₄σ₃₄-σ₁₃σ₂₃σ₄₄+σ₁₃σ₂₃ω₄₄,
-σ₁₄σ₂₃σ₂₄+σ₁₃σ₂₄²+σ₁₄σ₂₂σ₃₄-σ₁₃σ₂₂σ₄₄+σ₁₃σ₂₂ω₄₄

Total Effect of X₁ on X₄: λ₁₃λ₃₄

Vanishing Ideal

Constraint Set:

σ₁₂,
σ₁₄σ₂₃²-σ₁₃σ₂₃σ₂₄-σ₁₄σ₂₂σ₃₃+σ₁₃σ₂₂σ₃₄

All constraints are determinantal

Trek-separation:

{1} ⊥ {2} | ({},{})
{1,2,3} ⊥ {2,3,4} | ({},{2,3})