*	BIOSTAT 212: Introduction to Statistical Computing in Clinical Research
*	SUMMER 2017, TICR
*	Commands used in lecture and lab



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*    SESSION 1: Introduction, setting up .do files, basic exploring  		 
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clear all //clears all open data, variables, labels, matrices, memory and close all open files, graph windows, etc.
pwd // 'print working directory.' use it to check the current working directory. 
cd "/folder/path/here" //change working directory to where you want to save/import files from
capture log close // Close any existing log files 
log using lab1.log//open a log file
	log using lab1.log, replace //open an exisitng log file and replace it
	log using lab1.log, append //open an existing log file and append it
help dta_examples //information of built-in "system" data sets
sysuse "filename.dta" // open a built-in "system" like cancer.dta
	sysuse "filename.dta", clear // open a built-in "system" like cancer.dta and clear out any open data sets
browse // browse data in data editor
	br // browse shorthand
	browse "varlist" //browse specific variables 
describe // describes dataset and variables
	des //shorthand
summarize  //summarize data set (CONTINUOUS VARIABLES) 
	sum //shorthand
	sum "varlist" //summarize specific variables 
count // counts the number of observations
tabulate "varname" // tabulate 1 variable (CATEGORICAL VARIBALES)
	tab	//shorthand
	tab "varname1" "varname2" // tabulate 2 variables
	tab "varname1" "varname2", row // tabulate 2 variables with row percentages
	tab "varname1" "varname2", col // tabulate 2 variables with column percentages
log close //save and close log file 

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*    SESSION 2: Immediate commands and more exploring 		 
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di //use stata like a calculator
	di log(125)
	di 3+4
	di 10000/8
	di runiform(1,1000) //random number between 1 and a 1000
webuse "datasetname" //download dataset from the web
ds // check out variable names only
db "command" //open dialog box for a command
	db tabulate //for example
list "varname1" "varname2" //list specific variables
	list in 1/3 //list first 3 variables
	list in -50/l //list last 50 variables
gsort- "varname" // sort decending 
	gsort+ "varname" // sort ascending
codebook "varname"  // shows the contents of the variable, range
inspect "varname" //shows mini histogram
summarize  //summarize data set (CONTINUOUS VARIABLES) 
	sum //shorthand
	sum "varlist" //summarize specific variables 
	sum "varname", detail //detailed summary with median and percentiles
	bysort "varname1": sum "varname2" //summarize variable2 by a categorical variable1
duplicates report //report any duplicate observations
	duplicates report "varname" //report duplicates for a specific variable 
isid "varname" //does varname uniquely identify variables. no return value means "yes"