我是Stata的初学者，我正试图找出面板数据分析。我想弄清楚的第一件事是如何对常见变量进行汇总统计，比如说年份。我的数据看起来像
2010 5
2009 5
2010 3
2008 2
2010 12
2009 ...
显然，我有更多的数据，但我想弄清楚某一年的平均值（例如2010年）
我是否需要使用我的命令：mean variable, i(year)？
答案 0 :(得分：1)
有几种方法可以给猫皮肤涂抹：
. webuse nlswork, clear
(National Longitudinal Survey. Young Women 14-26 years of age in 1968)
. bysort year: sum ln_wage
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 68
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1375 1.44136 .3884235 .0176546 2.853805
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 69
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1232 1.531032 .3766929 .0240972 3.204134
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 70
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1686 1.507048 .3984743 .0240972 3.005013
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 71
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1851 1.546859 .414415 .0253174 3.285639
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 72
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1693 1.567283 .4319477 .0682788 4.242752
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 73
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1981 1.578448 .4297621 .0080322 3.757158
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 75
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 2141 1.579865 .4077728 .0622126 3.925446
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 77
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 2171 1.658813 .4308272 .0044871 3.623841
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 78
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1964 1.71629 .4327877 .0684925 4.029306
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 80
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1847 1.729773 .4442248 .1438704 4.199647
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 82
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 2085 1.726432 .46796 0 4.254619
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 83
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 1987 1.768276 .5140673 0 4.828314
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 85
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 2085 1.831842 .5063103 .0300107 4.025415
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 87
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 2164 1.841969 .5201446 .0441609 4.005049
----------------------------------------------------------------------------------------------------------------------------------------------------
-> year = 88
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
ln_wage | 2272 1.879937 .5960048 .0049397 5.263916
. tabstat ln_wage , by(year) stat(mean)
Summary for variables: ln_wage
by categories of: year (interview year)
year | mean
---------+----------
68 | 1.44136
69 | 1.531032
70 | 1.507048
71 | 1.546859
72 | 1.567283
73 | 1.578448
75 | 1.579865
77 | 1.658813
78 | 1.71629
80 | 1.729773
82 | 1.726432
83 | 1.768276
85 | 1.831842
87 | 1.841969
88 | 1.879937
---------+----------
Total | 1.674907
--------------------
. table year, c(mean ln_wage)
-------------------------
interview |
year | mean(ln_wage)
----------+--------------
68 | 1.44136
69 | 1.531032
70 | 1.507048
71 | 1.546859
72 | 1.567283
73 | 1.578448
75 | 1.579865
77 | 1.658813
78 | 1.71629
80 | 1.729773
82 | 1.726432
83 | 1.768276
85 | 1.831842
87 | 1.841969
88 | 1.879937
-------------------------