help vmergeVersion 1.0

Title

vmerge -- Verbose merge: a wrapper for the Stata merge command that provides additional details regarding the results of the update and replace options.

Syntax

vmerge
[merge_specification]
[, merge_options verbose conservememory ]

Main
merge_options are options of merge. See help on merge.

verbose even more verbose output

conservememory alternate method that conserves memory but uses more disk and CPU.

Description

This command provides a summary table that lists each variable in the master data set and indicates how many variables were affected by the
merge update and replace options. This summary table only reflects observations that are in the master data set (_merge==1, 3, 4, and 5).

This command sends merge_specification and merge_options to the Stata merge command without modification, without comment,
and without any assessment as to whether using the verbose merge makes sense. If the syntax is incorrect, the Stata merge command will let you know.

Warning: this command temporarily duplicates all variables in the master data set, thus requiring additional memory
equal to the size of the master data set. The conservememory option eliminates the need to use this
additional memory, but uses more disk space, takes longer, and results in more cryptic output.

Options

verbose For each variable in the master data set, gives a lists of observations where that variable was updated or replaced.

conservememory Performs the merge twice (with and without update/replace), compares the results using cf, and restores
the session to the desired condition after the requested merge. If the verbose option is specified it is passed to cf.

Author

Joseph Canner

Johns Hopkins University School of Medicine

Department of Surgery

Center for Surgical Trials and Outcomes Research

Email jcanner1@jhmi.edu