Drop variables with missing values

[Ana Vasconcelos]

I have a dataset with several variables and I want to remove all the variables that have more than 400 observations with missing data. Can you help me with this code?
Thank you very much

[Hemanshu Kumar]

foreach var of varlist * {
    count if missing(`var')
    if `=r(N)' > 400 drop `var' 
}

[Nick Cox]

Hemanshu Kumar gave a fine answer.

In addition, missings from the Stata Journal offers a systematic way of reporting on missing values.

An otherwise unpredictable search term for sources or mentions here is dm0085 (Rightly or wrongly, I didn't want a long command name such as missingsreport -- yet the name I used will trigger many hits if used as a search term.)

. search dm0085, entry

Search of official help files, FAQs, Examples, and Stata Journals

SJ-20-4 dm0085_2  . . . . . . . . . . . . . . . . Software update for missings
        (help missings if installed)  . . . . . . . . . . . . . . .  N. J. Cox
        Q4/20   SJ 20(4):1028--1030
        sorting has been extended for missings report

SJ-17-3 dm0085_1  . . . . . . . . . . . . . . . . Software update for missings
        (help missings if installed)  . . . . . . . . . . . . . . .  N. J. Cox
        Q3/17   SJ 17(3):779
        identify() and sort options have been added

SJ-15-4 dm0085  Speaking Stata: A set of utilities for managing missing values
        (help missings if installed)  . . . . . . . . . . . . . . .  N. J. Cox
        Q4/15   SJ 15(4):1174--1185
        provides command, missings, as a replacement for, and extension
        of, previous commands nmissing and dropmiss

missings doesn't offer a direct route to dropping variables or observations unless all observations or all variables respectively are missing. But it helps guide your decision-making.

. webuse nlswork, clear
(National Longitudinal Survey of Young Women, 14-24 years old in 1968)

. missings report

Checking missings in all variables:
15082 observations with missing values

-------------------
          |      #
----------+--------
      age |     24
      msp |     16
  nev_mar |     16
    grade |      2
 not_smsa |      8
   c_city |      8
    south |      8
 ind_code |    341
 occ_code |    121
    union |   9296
   wks_ue |   5704
   tenure |    433
    hours |     67
 wks_work |    703
-------------------

. missings report, sort min(400)

Checking missings in all variables:
15082 observations with missing values

-------------------
          |      #
----------+--------
    union |   9296
   wks_ue |   5704
 wks_work |    703
   tenure |    433
-------------------

. return list

scalars:
                  r(N) =  28534

macros:
            r(varlist) : "union wks_ue tenure wks_work"

.

[Ana Vasconcelos]

It worked. Thank you very much for your message.