如何從斜率為零的價格消費曲線中確定 PED？
給定兩種商品的預算 $ x_1 $ 和 $ x_2 $ , 商品 2 的固定價格和商品 1 的三個價格以及相應的商品 1 的最優數量 ( $ x_1 $ )，我喜歡計算好 1 的 PED。
通過查看給定的三個點，我知道商品 1 的價格消費曲線是一條水平曲線，即價格消費曲線的斜率似乎為零（連接三個點）。
Since I know the price ratio, I also know the MRS for the three given points.
So I have to find $ x_1(p_1, p_2, m) $ , where $ p_2 $ and $ m $ are known constants, in order to determine $ \partial x_1(…)/\partial p_1 $ .
What is the correct approach to this problem?
Since you have discrete datapoints and want to calculate PED, you will have to make assumptions, like “the data represents the general behavior of the consumption function”. (You can also get more data or throw your hands up in despair.)
If you know that price has no effect on the quantity demanded, you can apply the PED formula, and get a very specific number for PED.