In line 11, you declare a proxy variable to use to invoke the service.

11行，声明了一个代理变量以激活服务。

youdao

The trick is to find an “instrumental variable” which can act as a proxy for one variable in a statistical analysis, but which is clearly unrelated to the others.

诀窍在于找到一种“工具性可变因素”，它能在统计分析中代替某种可变因素，但它显然与其他可变因素无关。

youdao

But unlike Global Insight, they use a proxy for the first variable that is not itself affected by the second.

ECONOMIST: Measuring the Wal-Mart effect