mvencode、mvdecode

• 异常值处理
• mvencode将缺失值改为指定数值
• mvdecode把指定数值改为缺失值

describe/des

• 显示数据类型及格式、标签等

label

• 添加标签
• label data：数据集标签
• label variable：变量标签
• label define：自定义标签（中间变量）
• label values：值标签，会改变数据
• labelbook：查看已定义的标签

. sysuse auto, clear
(1978 automobile data)

. mvencode _all, mv(999)
        make: string variable ignored
       rep78: 5 missing values recoded

. edit

. mvdecode _all, mv(999)
        make: string variable ignored
       rep78: 5 missing values generated

. edit

. mvencode _all, mv(100000)
        make: string variable ignored
       rep78: 5 missing values recoded
              (recast to long)

. mvdecode _all, mv(100000)
        make: string variable ignored
       rep78: 5 missing values generated

. mvencode rep78, mv(999)
       rep78: 5 missing values recoded

. mvdecode rep78, mv(999)
       rep78: 5 missing values generated

. sysuse auto, clear
(1978 automobile data)

. des

Contains data from D:\software\Stata 17\ado\base/a/auto.dta
 Observations:            74                  1978 automobile data
    Variables:            12                  13 Apr 2020 17:45
                                              (_dta has notes)
-------------------------------------------------------------------------------
Variable      Storage   Display    Value
    name         type    format    label      Variable label
-------------------------------------------------------------------------------
make            str18   %-18s                 Make and model
price           int     %8.0gc                Price
mpg             int     %8.0g                 Mileage (mpg)
rep78           int     %8.0g                 Repair record 1978
headroom        float   %6.1f                 Headroom (in.)
trunk           int     %8.0g                 Trunk space (cu. ft.)
weight          int     %8.0gc                Weight (lbs.)
length          int     %8.0g                 Length (in.)
turn            int     %8.0g                 Turn circle (ft.)
displacement    int     %8.0g                 Displacement (cu. in.)
gear_ratio      float   %6.2f                 Gear ratio
foreign         byte    %8.0g      origin     Car origin
-------------------------------------------------------------------------------
Sorted by: foreign

. label data "This is a dataset"

. des

Contains data from D:\software\Stata 17\ado\base/a/auto.dta
 Observations:            74                  This is a dataset
    Variables:            12                  13 Apr 2020 17:45
                                              (_dta has notes)
-------------------------------------------------------------------------------
Variable      Storage   Display    Value
    name         type    format    label      Variable label
-------------------------------------------------------------------------------
make            str18   %-18s                 Make and model
price           int     %8.0gc                Price
mpg             int     %8.0g                 Mileage (mpg)
rep78           int     %8.0g                 Repair record 1978
headroom        float   %6.1f                 Headroom (in.)
trunk           int     %8.0g                 Trunk space (cu. ft.)
weight          int     %8.0gc                Weight (lbs.)
length          int     %8.0g                 Length (in.)
turn            int     %8.0g                 Turn circle (ft.)
displacement    int     %8.0g                 Displacement (cu. in.)
gear_ratio      float   %6.2f                 Gear ratio
foreign         byte    %8.0g      origin     Car origin
-------------------------------------------------------------------------------
Sorted by: foreign
     Note: Dataset has changed since last saved.

. save labeled.dta
file labeled.dta saved

. use labeled.dta, clear
(This is a dataset)

. sysuse auto, clear
(1978 automobile data)

. label define repair 1 "excellent" 2 "good" 3 "average" 4 "poor" 5 "fail"

. gen rep781 = rep78
(5 missing values generated)

. browse

. label values rep78 repair

. edit rep78 rep781

. label variable rep78 "ggg"