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关 键 词：销售stata软件怎样用
行 业：IT 软件 辅助设计
发布时间：2021-08-05
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讲座主题：因果推断: 内生性问题与工具变量法
讲座时间：5月19日15:00-16:00
讲座概述：因果推断模型与方法是现代社会科学研究者利用计量模型发表高水平实证论文的核心利器。其中，工具变量法则举足轻重，是计量研究中无法避开的挑战之一。此专题就内生性问题与解决路径、工具变量选择的方法及分类、工具变量的检验及工具变量回归模型（2SLS+GMM）等进行专题讨论，探讨工具变量法的基本思想、原理、模型、方法及适用范围，并以真实数据为演示案例，分享因果推断的思辨、工具变量回归模型的构建、应用及结果解读的路径，为发表高水平的实证研究论文奠定基础。
此外，我们还邀请了财经大学王存同教授，带来一场《因果推断：内生性问题与工具变量法》Stata讲座。
Multiple datasets in memory in Stata 16
You can now load multiple datasets into memory. You type
. use people
and people.dta is loaded into memory. Next, you type
. frame create counties
. frame counties: use counties
and you have two datasets in memory. people.dta is in the frame named default, and counties.dta is in the frame named counties. Your current frame is still default. Most Stata commands use the data in the current frame. For example, if you typed
. list
then people.dta will be listed. If you typed
. frame counties: list
then counties.dta will be listed. Or you could make counties the current frame by typing
. frame change counties
and list will now list the counties data.
Navigating frames is easy and so is linking them. Imagine that both datasets have a variable named countycode that identifies counties in the same way. Type
. frlink m:1 countycode, frame(counties)
and each person in the default frame is linked to a county in the counties frame. This means you can now use the frget command to copy variables from the counties frame to the current frame. Or you can use the frval() function to directly access the values of variables in the counties frame. For instance, if we have each individual’s income in the default frame and median county income in the counties frame, we can generate a new variable containing relative income by typing
. generate rel_income = income / frval(counties, median_income)
This is the beginning. While this example uses only two frames, you can have up to 100 frames in memory at once, and you can have many links among those frames.
generate’s sum() function creates the vertical, running sum of its argument, whereas egen’s
total() function creates a constant equal to the overall sum. egen’s rowtotal() function, however,
creates the horizontal sum of its arguments. They all treat missing as zero. However, if the missing
option is specified with total() or rowtotal(), then newvar will contain missing values if all
values of exp or varlist are missing.
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