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Lab 2 Four topics ：Do file , Data Management, Graphics and Test after estimation 1 Do file store the commands in a file same as Program Editor in SAS same as m-file in MATLAB the grammar of STATA: [by varlist:] command [varlist] [=exp] [if exp] [in range] [weight] [using filename] [, options] Example : create a do file and save it 2 Data Management (1) Stata commands in this unit cd Change directory memory Display a report on memory usage set memory Set the size of memory infile Read unformatted ASCII (text) data clear Clear the entire dataset and everything else input Enter data from keyboard save Store the dataset currently in memory on disk in Stata data format use Load a Stata-format dataset describe Describe contents of data in memory or on disk count Show the number of observations list List values of variables label data Apply a label to a data set label variable Apply a label to a variable rename Rename a variable generate Creates a new variable keep if Keep observations if condition is met keep Keep variables or observations drop Drop variables or observations append Append a data file to current file sort Sort observations merge Merge a data file with current file (2) Example: cd d:\stata /*the folder of my Stata dataset*/ memory set memory 200m infile str20 month RM_RF SMB HML RF using ff.txt, clear input id str20 name math 1 “Jim” 95 2 “Lucy” 80 3 “Li Lei” 90 end save math1 input id str20 name math 4 “Carl” 100 end save math2 input id str20 name economics 1 “Jim” 90 2 “Lucy” 90 3 “Li Lei” 85 4 “Carl” 95 end save economics use math1 describe count list use math1 label data “grade” label variable id “the student ID” label variable name “the student name” label variable math “the student grade of math” rename math Chinese rename Chinese math gen meanmath=90 gen devmath=math-meanmath use GPA, cl