📉 需求收入弹性Income Elasticity of Demand

使用说明与常见问题How-to & FAQ

「需求收入弹性」是什么？What is the Income Elasticity of Demand tool?

Ey = (%ΔQ) / (%ΔI)。本地处理。可设置「需求变化 %」、「收入变化 %」。Ey = (%ΔQ) / (%ΔI). Processed locally. Settings: Qty change %, Income change %.

如何使用「需求收入弹性」？How do I use the Income Elasticity of Demand tool?

在「需求收入弹性」中，填写「需求变化 %」、「收入变化 %」等参数，结果会随输入实时计算并显示在下方。In the Income Elasticity of Demand: Fill in "Qty change %", "Income change %"; results are recalculated instantly as you type.

怎么判断是奢侈品还是必需品？How do I tell luxury from necessity?

收入弹性 = 需求变化百分比 ÷ 收入变化百分比。大于 1 通常称为奢侈品（需求随收入增长更快），0 到 1 之间是必需品，小于 0 是劣等品。Income elasticity = % change in quantity ÷ % change in income. Above 1 usually means a luxury, 0 to 1 a necessity, and below 0 an inferior good.

能举个计算实例吗？Can you show a worked example?

例如在「需求收入弹性」中填 需求变化 % = 10，收入变化 % = 5，结果区显示：收入弹性：2For example, entering Qty change % = 10, Income change % = 5 in the Income Elasticity of Demand gives: Income elasticity: 2

哪些输入会被检查？Which inputs are validated?

「需求收入弹性」会检查这些输入——「需求变化 %」、「收入变化 %」：必须填写；绝对值超过 10¹⁵ 的数也会被拒绝。不符合时结果区显示具体提示，不会给出数字。The Income Elasticity of Demand checks its inputs — "Qty change %", "Income change %": required; numbers above 10¹⁵ in absolute value are rejected too. When a value fails, the result area names the problem instead of showing a number.

有哪些选项可以调整？What options can I adjust?

「需求收入弹性」的设置：「需求变化 %」默认 10；「收入变化 %」默认 5。每次生成结果都按当前设置处理。Settings in the Income Elasticity of Demand — "Qty change %" default 10; "Income change %" default 5. The result always uses the current settings.

计算结果可以作为最终依据吗？Can I rely on the result?

「需求收入弹性」按标准公式计算，结果仅供参考；实际金额以银行、券商或税务机关的规则和四舍五入方式为准。The Income Elasticity of Demand uses standard formulas and is for estimation only; actual figures depend on your bank, broker or tax authority's rules and rounding.

「需求收入弹性」免费吗？需要注册吗？Is the Income Elasticity of Demand free? Do I need an account?

「需求收入弹性」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Income Elasticity of Demand is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.