//检测缺失值方法：
//用.表示缺失值，将缺失值定义为无穷大
//方法一：检测当前行有几个变量是缺失值，Stata执行描述性统计命令时，会自动忽略变量的缺失值；执行回归命令时，如果其中某个变量包含缺失值，Stata忽略这个变量所属观测值上所有变量取值
egen miss=rowmiss(_all)
//方法二：检测当前行以pidhaizi开头的变量有几个是缺失值
egen miss=rowmiss(pidhaizi*)
//方法三：分别统计每个变量分别有几个缺失值
//安装
ssc install nmissing
// checking nmissing consistency and verifying not already installed...
// installing into C:\Users\admin\ado\plus\...
// installation complete.
. nmissing
// age 51476
// pidhaizi 42208
// pidhaizia 42964
// pidhaizib 85696
// pidhaizic 88235
// pidhaizid 88662
// pidhaizie 88771
// pidhaizif 88808
// pidhaizig 88828
//方法四：
. codebook age
// ---------------------------------------------------------------------------
// age 年龄
// ---------------------------------------------------------------------------
// Type: Numeric (double)
// Label: age, but 93 nonmissing values are not labeled
// Range: [-8,102] Units: 1
// Unique values: 94 Missing .: 51,476/88,830
// Examples: 44
// 76
//方法五：
ssc install mdesc
mdesc
// Variable | Missing Total Percent Missing
// ----------------+-----------------------------------------------
// pid | 0 88,830 0.00
// fid18 | 0 88,830 0.00
// age | 51,476 88,830 57.95
// pidhaizi | 42,208 88,830 47.52
// pidhaizia | 42,964 88,830 48.37
// pidhaizib | 85,696 88,830 96.47
// pidhaizic | 88,235 88,830 99.33
// pidhaizid | 88,662 88,830 99.81
// pidhaizie | 88,771 88,830 99.93
// pidhaizif | 88,808 88,830 99.98
// pidhaizig | 88,828 88,830 100.00
// miss | 0 88,830 0.00
// conta | 0 88,830 0.00
// ----------------+-----------------------------------------------
