Income Effect


Income effect refers to the change in quantity consumed due to the change in real income, holding relative price constant.

Income effect 是在相對價格不變的情況下,「實質所得」改變所帶來的消費數量改變。

【有關實質所得 (real income) 與貨幣所得 (money income) 的討論,請看 < real income and utility> 一文。】

Income effects - positive; negative & zero

1. Positive income effect & normal good

實質所得與消費數量是「正向關係」(positive relationship)。這是說在相對價格不變下,若實質所得上升 ,消費數量也會上升 。反之,若實質所得下降,消費數量也會下降。

當 positive income effect 出現在某經濟物品上時,這經濟物品便是 normal good

2. Negative income effect & Inferior good

實質所得與消費數量是「反向關係」(negative relationship)。這是說在相對價格不變下,若實質所得上升 ,消費數量會下降 。反之,若實質所得下降,消費數量也會上升。

當 negative income effect 出現在某經濟物品上時,這經濟物品便是 inferior good

3. Zero income effect


Income effect 圖解:




Econman (29 /8/ 2000)

Indifference Curve Analysis





<1> Preference & Utility

Marginal rate of substitution
Diminishing marginal rate of substitution

<3> Indifference curve & its properties
<4> Special Cases (I)
<5> Special Cases (II)
<6> Budget constraints
<7> Consumer optimal & corner solution
<8> Real Income & Utility
<9> Income effect
<10> Substitution effect
<11> Price effect
<12> Price effect - Decomposition
<13> Giffen Good



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