data analysis using stata - reed college€¦ · data analysis using stata kristin bott kbott @...

DataAnalysisusingStata

KristinBottkbott @reed.edu

<<Logintoacomputerwhileyou’rewaiting>>

K.Bott /InstructionalTechnologyServicesReedCollege/Portland,OR

blogs.reed.edu/datablog

Intro/K.Bott+Data@ReedAssociateDirector,[email protected] /ETC225

Geospatial/Statistical/ComputationalsoftwareDataanalysis+presentation

Data@Reed :[email protected]/data-at-reed

averyskeletalresearchprocess

Question


Data

Results

Conclusions

data@reed/research+datasupport

Datadiscovery


Datavisualization

Datacitation

Dataanalysis

Datamanagement

Datawrangling

Wherewe’reheaded(<60min)

• Stepzero:howtofindandpilotStata• Stepone:basicdataskills• Steptwo:externaldata• Stepthree:dataanalysis• Helpandresources


wheretofind/howtoaccess

WhereyoucanfindStata• Aroundcampus:– IRC’s(ETC)– Library– Eliot110/PPW(socialsciences)– Psychologycomputerlab

• “GradPlan”/optionforbuyingyourowncopy


AccessingStata

Onyourcomputers-->Applications

>>StataSE

openStata !

…andlet’stakealook.


Review Variables

(variable)propertiesCommand

Results

WhatdidIdo?WhatdataamIworkingwith?

DatadetailsCurrentactionishere!

Whathappened?

• Point+click(GUI)vs command-line

Stata datasets

• Pre-loaded,usefulfortraining/learning• Type:

. set more off

. sysuse dir

. sysuse auto(1978 Automobile data)


stata:basicdataskills

Dataisloaded:nowwhat?

Whatsortofinformationdoyouwanttoknowaboutyourdata?

Howcanwegettothisinformation?


Somethingsyoumaywanttoknow

Range ofdata/outliersMissing values[Howmany?Howcoded?]

Types ofvariablesVariation ofdata

(stepone:lookatyourdata– databrowser).browse


first-glancetools

.summarize (wholedataset)

.summarize rep78Observation/mean/StdDev /Min/Max

.describe (wholedataset)

.describe [var]var name/storagetype/disp format/valuelabel/var label

.codebook (wholedataset)

.codebook [var]type/range/units/unique/missing/mean/std dev /%tiles

first-glancetools


.summarize [var]Observation/mean/StdDev /Min/Max


.describe rep78var name/storagetype/disp format/valuelabel/var label



first-glancetools







Variablestoragetypes

• Describe orvariablewindowshows“storagetype”

• Numbers– byte,int(eger),long,float,double– varyinprecision+memorytheyuse(bytes)

• Letters:– String– str1,str2,…str244

• Question::Whydoesthismatter?


Variablestoragetypes

• Describe orvariablewindowshows“storagetype”

• Numbers– byte,int(eger),long,float,double– varyinprecision+memorytheyuse(bytes)

• Letters:– String– str1,str2,…str244

• Question::Whydoesthismatter?


Youcan’tfindthemeanofwords...

first-glancetools






.codebook rep78type/range/units/unique/missing/mean/std dev /%tiles

first-glancetools







somefirst-glancetools

.tabulate foreignvariable/frequency/percent/cumulative%

.tabulate [var1] [var2]whatdoesthisdo?




.tabulate (wholedataset)

.tabulate [var]variable/frequency/percent/cumulative%

.tabulate foreign rep78whatdoesthisdo?




.tabulate (wholedataset)

.tabulate [var]variable/frequency/percent/cumulative%

.tabulate make rep78whatdoesthisdo?



Hmm…doIhaveobservationsforthesamemake+repairrecord?

kbott’s first-glancetoolbox

Fordataset or[var]or[var1][var2].summarize.codebook.describe.tabulate.inspect .browse.list


belazy!– useonlyafew(unique)lettersforcommands

Basics:[browse]subsetsofdata

browse if foreign == 1 (equals)browse if foreign ~= 1 (notequal)browse if foreign != 1 (notequal)

browse if mpg > 5 & mpg < 20 (&joinsmultiple)

browse make mpg in 1/10(rangeofvalues)


Canalsouseview toseeresultsinmainwindow

Basics:alterdata

.sort var (sortsfromlowtohigh)

.drop var (dropvariable,keeprest)

.keep var (keepvariable,droprest)

.replace var (replaceexistingvariable)

.generate var (generatenewvariable)

.egen var (extendedgenerate)

.clear [dataset](clearsfrommemory,doesnot erasedata)

dataanalysis+visualization

Basics(stockdataset)

• Histograms. sysuse auto. hist price, freq. hist price, freq bin(5). hist price, freq bin(15)

. hist price if foreign==1, freq bin(15)


Basics(stockdataset)

• Scatterplots. sysuse auto. scatter mpg weight. scatter mpg weight || lfit mpg weight


Analyze:twovariables

. correlate mpg weight

. regress mpg weight


Analyze:twovariables

. correlate mpg weight

. regress mpg weight

Examinerelationshipbyforeign/domesticvehicles. by foreign: regress mpg weight

Examinerelationshipforonlyforeignvehicles. regress mpg weight if foreign==1


Homework#3

additional+specifictools

Homework#3

• Measuresofcentraltendency+dispersion. summarize. tabulate

• Visualization. scatter

• Analysis. regress. predict


Homework#3

• Measuresofcentraltendency+dispersion. summarize. tabulate

• Visualization. scatter

• Analysis. regress. predict. help predict


Help+additionalresources

Help!+additionaltools

• Stata HelpMenu– contents– search– command

• Atthecommandline– help– search– findit

• External(toStata)resources• Trackworkviadofiles


Keytocollaboration:Dofiles

SaveyoutimeforrepetitioustasksMinimizeserrorsStoreyourdataanalysisprocess

.doeditorviaGUI

Kbott OfficeHoursbyappointment

helpdocumentation+moreD@Rsite:reed.edu/data-at-reed

[email protected] |ETC225

data analysis using stata - reed college€¦ · data analysis using stata kristin bott kbott @...

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