官方教材2007版，Reading 13，Summary部分有错误 percentage, demand, income, normal

chenty

2007版官方教材Reading 13（Elasticity）的SUMMARY部分（P.32）

原文：

When the income elasticity of demand is greater than 1, the percentage of income spent on the good increases as income increases.

When the income elasticity of domand is less than 1 but greater than zero, the percentage of income spent on the good decreases as income increases.

我认为这个结论不正确，如果income spent on good increases as income increases，应该是normal good，income elasticity应该是大于0，而不是大于1。

类似，如果income spent on good decreases as income increases，应该是inferor good，income elasticity应该是小于0，而不是大于0小于1。

请老师看看我的说法是否正确？

[此贴子已经被作者于2007-7-12 4:06:06编辑过]

胡老师

When the income elasticity of domand is less than 1 but greater than zero, the percentage of income spent on the good decreases as income increases.　我认为这个话是错误的，收入的弹性系数大于0小于１的话，是正常的商品，收入上升，需求也是上升的，只是上升的幅度比收入小而已。而大于１的为奢侈品，小于0的为劣等品。我同意你的看法