问题描述:
help help me 翻译成中文啦~~~急
The key identifying assumption of our analysis is that countries' geographic characteristics (their Pi's and Si's) are uncorrelated with the residuals in equations (1) and (3). Proximity and size are not affected by income or by other factors,such as government policies,that affect income. And as we observe in the introduction, it is difficult to think of important ways that proximity and size might affect income other than through their impact on how much a country's residents interact with foreigners and with one another.
Given the assumption that P and S are uncorrelated with E,data on Y,T,W,P and S would allow us to estimate equation (1) by instrumental variables: P and S are correlated with T and W [by (2) and (3)], and the uncorrelated with E (by our identifying assumption). Unfortunately, however, there are no data on within-country trade. Ideally,we would want data comparable to measures of international trade. That is,we would want a measure of the value of the exchange of all goods and services among individuals within a country, both across and within firms. This measure would probably be many times GDP for most countries. But no such measure exists.
The key identifying assumption of our analysis is that countries' geographic characteristics (their Pi's and Si's) are uncorrelated with the residuals in equations (1) and (3). Proximity and size are not affected by income or by other factors,such as government policies,that affect income. And as we observe in the introduction, it is difficult to think of important ways that proximity and size might affect income other than through their impact on how much a country's residents interact with foreigners and with one another.
Given the assumption that P and S are uncorrelated with E,data on Y,T,W,P and S would allow us to estimate equation (1) by instrumental variables: P and S are correlated with T and W [by (2) and (3)], and the uncorrelated with E (by our identifying assumption). Unfortunately, however, there are no data on within-country trade. Ideally,we would want data comparable to measures of international trade. That is,we would want a measure of the value of the exchange of all goods and services among individuals within a country, both across and within firms. This measure would probably be many times GDP for most countries. But no such measure exists.
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