STATA 10 Introduction

Title first—Introduction andfirst sessionDescription Remarks and examples Also seeDescriptionMata is a component of Stata.It is a matrix programming language that can be used interactively or as an extension for do-files and ado-files.Thus1.Mata can be used by users who want to think in matrix terms and perform(not necessarilysimple)matrix calculations interactively,and2.Mata can be used by advanced Stata programmers who want to add features to Stata.Mata has something for everybody.Primary features of Mata are that it is fast and that it is C-like.Remarks and examples This introduction is presented under the following headings:Invoking MataUsing MataMaking mistakes:Interpreting error messagesWorking with real numbers,complex numbers,and stringsWorking with scalars,vectors,and matricesWorking with functionsDistinguishing real and complex valuesWorking with matrix and scalar functionsPerforming element-by-element calculations:Colon operatorsWriting programsMore functionsMata environment commandsExiting MataIf you are reading the entries in the order suggested in[M-0]intro,see[M-1]interactive next. Invoking MataTo enter Mata,type mata at Stata’s dot prompt and press enter;to exit Mata,type end at Mata’s colon prompt:.mata←type mata to enter Matamata(type end to exit):2+2←type Mata statements at the colon prompt4:end←type end to return to Stata._←you are back to Stata12first—Introduction andfirst sessionUsing MataWhen you type a statement into Mata,Mata compiles what you typed and,if it compiled without error,executes it::2+24:_We typed2+2,a particular example from the general class of expressions.Mata responded with4, the evaluation of the expression.Often what you type are expressions,although you will probably choose more complicated examples.When an expression is not assigned to a variable,the result of the expression is displayed.Assignment is performed by the=operator::x=2+2:x4:_When we type“x=2+2”,the expression is evaluated and stored in the variable we just named x.The result is not displayed.We can look at the contents of x,however,simply by typing“x”.From Mata’s perspective,x is not only a variable but also an expression,albeit a rather simple one.Just as 2+2says to load2,load another2,and add them,the expression x says to load x and stop there.As an aside,Mata distinguishes uppercase and lowercase.X is not the same as x::X=2+3:x4:X5:_Making mistakes:Interpreting error messagesIf you make a mistake,Mata complains,and then you continue on your way.For instance, :2,,3invalid expressionr(3000);:_2,,3makes no sense to Mata,so Mata complained.This is an example of what is called a compile-time error;Mata could not make sense out of what we typed.The other kind of error is called a run-time error.For example,we have no variable called y.Let us ask Mata to show us the contents of y::y<istmt>:3499y not foundr(3499);:_first—Introduction andfirst session3 Here what we typed made perfect sense—show me y—but y has never been defined.This ugly message is called a run-time error message—see[M-2]errors for a complete description—but all that’s important is to understand the difference betweeninvalid expressionand<istmt>:3499y not foundThe run-time message is prefixed by an identity(<istmt>here)and a number(3499here).Mata is telling us,“I was executing your istmt[that’s what everything you type is called]and I got error 3499,the details of which are that I was unable tofind y.”The compile-time error message is of a simpler form:invalid expression.When you get such unprefixed error messages,that means Mata could not understand what you typed.When you get the more complicated error message,that means Mata understood what you typed,but there was a problem performing your request.Another way to tell the difference between compile-time errors and run-time errors is to look at the return pile-time errors have a return code of3000::2,,3invalid expressionr(3000);Run-time errors have a return code that might be in the3000s,but is never3000exactly: :y<istmt>:3499y not foundr(3499);Whether the error is compile-time or run-time,once the error message is issued,Mata is ready to continue just as if the error never happened.Working with real numbers,complex numbers,and stringsAs we have seen,Mata works with real numbers::2+35Mata also understands complex numbers;you write the imaginary part by suffixing a lowercase i: :1+2i+4-1i5+1iFor imaginary numbers,you can omit the real part::1+2i-2i1Whether a number is real or complex,you can use the same computer notation for the imaginary part as you would for the real part::2.5e+3i2500i:1.25e+2+2.5e+3i/*i.e.,1.25+e02+2.5e+03i*/125+2500i4first—Introduction andfirst sessionWe purposely wrote the last example in nearly unreadable form just to emphasize that Mata could interpret it.Mata also understands strings,which you write enclosed in double quotes::"Alpha"+"Beta"AlphaBetaJust like Stata,Mata understands simple and compound double quotes::‘"Alpha"’+‘"Beta"’AlphaBetaYou can add complex and reals,:1+2i+34+2ibut you may not add reals or complex to strings::2+"alpha"type mismatch:real+string not allowedr(3000);We got a run-time error.Mata understood2+"alpha"all right;it just could not perform our request. Working with scalars,vectors,and matricesIn addition to understanding scalars—be they real,complex,or string—Mata understands vectors and matrices of real,complex,and string elements::x=(1,2):x12112x now contains the row vector(1,2).We can add vectors::x+(3,4)12146The“,”is the column-join operator;things like(1,2)are expressions,just as(1+2)is an expression::y=(3,4):z=(x,y):z123411234In the above,we could have dispensed with the parentheses and typed“y=3,4”followed by“z= x,y”,just as we could using the+operator,although most peoplefind vectors more readable when enclosed in parentheses.first—Introduction andfirst session5\is the row-join operator::a=(1\2):a11122::b=(3\4):c=(a\b):c111223344Using the column-join and row-join operators,we can enter matrices::A=(1,2\3,4):A12112234The use of these operators is not limited to scalars.Remember,x is the row vector(1,2),y is the row vector(3,4),a is the column vector(1\2),and b is the column vector(3\4).Therefore, :x\y12112234:a,b12113224But if we try something nonsensical,we get an error::a,x<istmt>:3200conformability errorWe create complex vectors and matrices just as we create real ones,the only difference being that their elements are complex::Z=(1+1i,2+3i\3-2i,-1-1i):Z1211+1i2+3i23-2i-1-1i6first—Introduction andfirst sessionSimilarly,we can create string vectors and matrices,which are vectors and matrices with string elements::S=("1st element","2nd element"\"another row","last element"):S1211st element2nd element2another row last elementFor strings,the individual elements can be up to2,147,483,647characters long.Working with functionsMata’s expressions also include functions::sqrt(4)2:sqrt(-4).When we ask for the square root of−4,Mata replies“.”Further,.can be stored just like any other number::findout=sqrt(-4):findout.“.”means missing,that there is no answer to our calculation.Taking the square root of a negative number is not an error;it merely produces missing.To Mata,missing is a number like any other number,and the rules for all the operators have been generalized to understand missing.For instance, the addition rule is generalized such that missing plus anything is missing::2+..Still,it should surprise you that Mata produced missing for the sqrt(-4).We said that Mata understands complex numbers,so should not the answer be2i?The answer is that is should be if you are working on the complex plane,but otherwise,missing is probably a better answer.Mata attempts to intuit the kind of answer you want by context,and in particular,uses inheritance rules.If you ask for the square root of a real number,you get a real number back.If you ask for the square root of a complex number,you get a complex number back::sqrt(-4+0i)2iHere complex means multipart:-4+0i is a complex number;it merely happens to have0imaginary part.Thus::areal=-4:acomplex=-4+0i:sqrt(areal).:sqrt(acomplex)2ifirst—Introduction andfirst session7 If you ever have a real scalar,vector,or matrix,and want to make it complex,use the C()function, which means“convert to complex”::sqrt(C(areal))2iC()is documented in[M-5]C().C()allows one or two arguments.With one argument,it casts to complex.With two arguments,it makes a complex out of the two real arguments.Thus you could type:sqrt(-4+2i).485868272+2.05817103ior you could type:sqrt(C(-4,2)).485868272+2.05817103iBy the way,used with one argument,C()also allows complex,and then it does nothing: :sqrt(C(acomplex))2iDistinguishing real and complex valuesIt is virtually impossible to tell the difference between a real value and a complex value with zero imaginary part::areal=-4:acomplex=-4+0i:areal-4:acomplex-4Yet,as we have seen,the difference is important:sqrt(areal)is missing,sqrt(acomplex)is 2i.One solution is the eltype()function::eltype(areal)real:eltype(acomplex)complexeltype()can also be used with strings,:astring="hello":eltype(astring)stringbut this is useful mostly in programming contexts.8first—Introduction andfirst sessionWorking with matrix and scalar functionsSome functions are matrix functions:they require a matrix and return a matrix.Mata’s invsym(X) is an example of such a function.It returns the matrix that is the inverse of symmetric,real matrix X: :X=(76,53,48\53,88,46\48,46,63):Xi=invsym(X):Xi[symmetric]1231.029*******2-.0098470272.021*******3-.0155497706-.0082885675.0337724301:Xi*X12311-8.67362e-17-8.50015e-172-1.38778e-161-1.02349e-1630 1.11022e-161The last matrix,Xi*X,differs just a little from the identity matrix because of unavoidable computational roundoff error.Other functions are,mathematically speaking,scalar functions.sqrt()is an example in that it makes no sense to speak of sqrt(X).(That is,it makes no sense to speak of sqrt(X)unless we were speaking of the Cholesky square-root decomposition.Mata has such a matrix function;see [M-5]cholesky().)When a function is,mathematically speaking,a scalar function,the corresponding Mata function will usually allow vector and matrix arguments and,then,the Mata function makes the calculation on each element individually::M=(1,2\3,4\5,6):M12112234356::S=sqrt(M):S1211 1.4142135622 1.73205080823 2.236067977 2.449489743::S[1,2]*S[1,2]2:S[2,1]*S[2,1]3first—Introduction andfirst session9 When a function returns a result calculated in this way,it is said to return an element-by-element result.Performing element-by-element calculations:Colon operatorsMata’s operators,such as+(addition)and*(multiplication),work as you would expect.In particular, *performs matrix multiplication::A=(1,2\3,4):B=(5,6\7,8):A*B121192224350Thefirst element of the result was calculated as1∗5+2∗7=19.Sometimes,you really want the element-by-element result.When you do,place a colon in front of the operator:Mata’s:*operator performs element-by-element multiplication::A:*B12151222132See[M-2]op colon for more information.Writing programsMata is a complete programming language;it will allow you to create your own functions: :function add(a,b)return(a+b)That single statement creates a new function,although perhaps you would prefer if we typed it as :function add(a,b)>{>return(a+b)>}because that makes it obvious that a program can contain many lines.In either case,once defined, we can use the function::add(1,2)3:add(1+2i,4-1i)5+1i:add((1,2),(3,4))1214610first—Introduction andfirst session:add(x,y)12146:add(A,A)12124268::Z1=(1+1i,1+1i\2,2i):Z2=(1+2i,-3+3i\6i,-2+2i):add(Z1,Z2)1212+3i-2+4i22+6i-2+4i::add("Alpha","Beta")AlphaBeta::S1=("one","two"\"three","four"):S2=("abc","def"\"ghi","jkl"):add(S1,S2)121oneabc twodef2threeghi fourjklOf course,our little function add()does not do anything that the+operator does not already do, but we could write a program that did do something different.The following program will allow us to make n×n identity matrices::real matrix id(real scalar n)>{>real scalar i>real matrix res>>res=J(n,n,0)>for(i=1;i<=n;i++){>res[i,i]=1>}>return(res)>}::I3=id(3):I3[symmetric]123112013001The function J()in the program line res=J(n,n,0)is a Mata built-in function that returns an n×n matrix containing0s(J(r,c,val)returns an r×c matrix,the elements of which are all equal to val);see[M-5]J().for(i=1;i<=n;i++)says that starting with i=1and so long as i<=n do what is inside the braces(set res[i,i]equal to1)and then(we are back to the for part again),increment i.Thefinal line—return(res)—says to return the matrix we have just created.Actually,just as with add(),we do not need id()because Mata has a built-in function I(n)that makes identity matrices,but it is interesting to see how the problem could be programmed.More functionsMata has many functions already and much of this manual concerns documenting what those functions do;see[M-4]intro.But right now,what is important is that many of the functions are themselves written in Mata!One of those functions is pi();it takes no arguments and returns the value of pi.The code for it readsreal scalar pi()return(3.141592653589793238462643)There is no reason to type the above function because it is already included as part of Mata: :pi()3.141592654When Mata lists a result,it does not show as many digits,but we could ask to see more: :printf("%17.0g",pi())3.14159265358979Other Mata functions include the hyperbolic function tanh(u).The code for tanh(u)reads numeric matrix tanh(numeric matrix u){numeric matrix eu,emueu=exp(u)emu=exp(-u)return((eu-emu):/(eu+emu))}See for yourself:at the Stata dot prompt(not the Mata colon prompt),type.viewsource tanh.mataWhen the code for a function was written in Mata(as opposed to having been written in C), viewsource can show you the code;see[M-1]source.Returning to the function tanh(),numeric matrix tanh(numeric matrix u){numeric matrix eu,emueu=exp(u)emu=exp(-u)return((eu-emu):/(eu+emu))}this is thefirst time we have seen the word numeric:it means real or complex.Built-in(previously written)function exp()works like sqrt()in that it allows a real or complex argument and correspondingly returns a real or complex result.Said in Mata jargon:exp()allows a numeric argument and correspondingly returns a numeric result.tanh()will also work like sqrt()and exp().Another characteristic tanh()shares with sqrt()and exp()is element-by-element operation. tanh()is element-by-element because exp()is element-by-element and because we were careful to use the:/(element-by-element)divide operator.In any case,there is no need to type the above functions because they are already part of Mata.You could learn more about them by seeing their manual entry,[M-5]sin().At the other extreme,Mata functions can become long.Here is Mata’s function to solve AX=B for X when A is lower triangular,placing the result X back into A:real scalar_solvelower(numeric matrix A,numeric matrix b,|real scalar usertol,numeric scalar userd){real scalar tol,rank,a_t,b_t,d_treal scalar n,m,i,im1,complex_casenumeric rowvector sumnumeric scalar zero,dd=userdif((n=rows(A))!=cols(A))_error(3205)if(n!=rows(b))_error(3200)if(isview(b))_error(3104)m=cols(b)rank=na_t=iscomplex(A)b_t=iscomplex(b)d_t=d<.?iscomplex(d):0complex_case=a_t|b_t|d_tif(complex_case){if(!a_t)A=C(A)if(!b_t)b=C(b)if(d<.&!d_t)d=C(d)zero=0i}else zero=0if(n==0|m==0)return(0)tol=solve_tol(A,usertol)if(abs(d)>=.){if(abs(d=A[1,1])<=tol){b[1,.]=J(1,m,zero)--rank}else{b[1,.]=b[1,.]:/dif(missing(d))rank=.}for(i=2;i<=n;i++){im1=i-1sum=A[|i,1ı,im1|]*b[|1,1\im1,m|]if(abs(d=A[i,i])<=tol){b[i,.]=J(1,m,zero)--rank}else{b[i,.]=(b[i,.]-sum):/dif(missing(d))rank=.}}}else{if(abs(d)<=tol){rank=0b=J(rows(b),cols(b),zero)}else{b[1,.]=b[1,.]:/dfor(i=2;i<=n;i++){im1=i-1sum=A[|i,1ı,im1|]*b[|1,1\im1,m|]b[i,.]=(b[i,.]-sum):/d}}}return(rank)}If the function were not already part of Mata and you wanted to use it,you could type it into a do-file or onto the end of an ado-file(especially good if you just want to use solvelower()as a subroutine).In those cases,do not forget to enter and exit Mata:begin ado-fileprogram mycommand...ado-file code appears here...endmata:_solvelower()code appears hereendend ado-file Sharp-eyed readers will notice that we put a colon on the end of the Mata command.That’s a detail, and why we did that is explained in[M-3]mata.In addition to loading functions by putting their code in do-and ado-files,you can also save the compiled versions of functions in.mofiles(see[M-3]mata mosave)or into.mlib Mata libraries (see[M-3]mata mlib).For solvelower(),it has already been saved into a library,namely,Mata’s official library,so you need not do any of this.Mata environment commandsWhen you are using Mata,there is a set of commands that will tell you about and manipulate Mata’s environment.The most useful such command is mata describe;see[M-3]mata describe::mata describe#bytes type name and extent76transmorphic matrix add()200real matrix id()32real matrix A[2,2]32real matrix B[2,2]72real matrix I3[3,3]48real matrix M[3,2]48real matrix S[3,2]47string matrix S1[2,2]44string matrix S2[2,2]72real matrix X[3,3]72real matrix Xi[3,3]64complex matrix Z[2,2]64complex matrix Z1[2,2]64complex matrix Z2[2,2]16real colvector a[2]16complex scalar acomplex8real scalar areal16real colvector b[2]32real colvector c[4]8real scalar findout16real rowvector x[2]16real rowvector y[2]32real rowvector z[4]:_Another useful command is mata clear(see[M-3]mata clear),which will clear Mata without disturbing Stata::mata clear:mata describe#bytes type name and extentThere are other useful mata commands;see[M-3]intro.Do not confuse this command mata,which you type at Mata’s colon prompt,with Stata’s command mata,which you type at Stata’s dot prompt and which invokes Mata.Exiting MataWhen you are done using Mata,type end to Mata’s colon prompt::end._Exiting Mata does not clear it:.matamata(type end to exit):x=2:y=(3+2i):function add(a,b)return(a+b):end.....matamata(type end to exit):mata describe#bytes type name and extent76transmorphic matrix add()8real scalar x16complex scalar y:endExiting Stata clears Mata,as does Stata’s clear mata command;see[D]clear.Also see[M-1]intro—Introduction and advice。

Stata入门介绍Stata入门介绍转载，原作者不详。

(1) Stata要在使用中熟练的，大家应该多加练习。

(2) Stata的很多细节，这里不会涉及，只是选取相对重要的部分加以解释，大家在使用Stata过程中留心积累。

作为入门性质的介绍，本文只选取和中级计量经济学作业相关的内容和一些处理数据所使用的基本命令。

对于更高深的内容，请大家参看STATA manual.”界面当我们把stata装好以后，首先需要了解的是它的界面。

打开Stata后我们便可以看到它常用的四个窗口：Stata Results; Review; Variables; Stata Command。

我们所有的运行结果都会在Stata Results界面中显示；而命令的输入则在Stata Command窗口；Review窗口记录我们使用过的命令；最后Variables窗口显示存在于当前数据库中的所有变量的名称。

可以直接点击 Review窗口来重新输入已使用过的命令，我们所需变量可以通过点击Varaibles窗口来得到，这些都可以简便我们的操作。

Stata 命令Stata软件功能强大，体现在它提供了丰富的命令，可以实现许多功能。

每一个stata命令都相应的命令格式。

我们在这里介绍常用的一些命令的功能和相应的格式，大家在使用stata的过程中会不断积累命令的相关知识。

需要对命令的帮助时可以用help命令查询。

例如了解命令：“reg” ，就可以在Stata Command窗口输入“help reg” ，也可以在Help选项下content中查找我们需要的相关命令。

用help查询，则窗口会显示关于该命令的详尽说明。

更直接的办法是看Examples中的范例是如何使用该命令，阅读一些相关的说明并加以模仿。

重要习惯我们使用stata进行回归分析时，需要养成一些好的习惯。

在进行一些数据量很大，过程复杂的分析时尤其重要。

（1）使用日志（log）。

它可以帮助我们记录stata的运行结果。

18Learning more about StataWhere to go from hereYou now know plenty enough to use Stata.There is still much,much more to learn because Stata is a rich environment for doing statistical analysis and data management.What should you do to learn more?•Get an interesting dataset and play with Stata.e the menus and dialog system to experiment with commands.Notice what commandsshow up in the Results window.You willfind that Stata’s simple and consistent commandsyntax will make the commands easy to read so that you will know what you have doneand easy to remember so that typing some commands will be faster than using menus.b.Play with graphs and the Graph Editor.•If you venture into the Command window,you willfind that many things will go faster.You will alsofind that it is possible to make mistakes where you cannot understand why Stata is balking.a.Try help commandname or Help>Stata command...and entering the command name.b.Look at the command syntax and the examples in the helpfile,and compare themwith what you pare them closely:small typographical errors make commandsimpossible for Stata to parse.•Explore Stata by selecting Help>Search....You will uncover many statistical routines that could be of great use.•Look through the Combined subject table of contents in the Stata Index.•Read and work your way through the User’s Guide.It is designed to be read from cover to cover,and it contains most of the information you need to become an expert Stata user.It is well worth reading.If you are not this ambitious and instead prefer to sample the User’s Guide and the references,there is some advice later in this chapter for you.•Browse through the reference manuals to read about statistical methods you like to use,making use of the links to jump to other topics.The reference manuals are not meant to be read from cover to cover—they are meant to be referred to as you would an encyclopedia.You canfind the datasets used in the examples in the manuals by selecting File>Example datasets...and then clicking on Stata18manual datasets.Doing so will enable you to work through the examples quickly.•Stata has much information,including answers to frequently asked questions(FAQ s),at https:///support/faqs/.•There are many useful links to Stata resources at https:///links/.Be sure to look at these materials because many outstanding resources about Stata are listed here.•Join Statalist,a forum devoted to discussion of Stata and statistics.•Read The Stata Blog:Not Elsewhere Classified at https:// to read articles written by people at Stata about all things Stata.•Visit Stata on Facebook at https:///statacorp,join Stata on Instagram at https:///statacorp,find Stata on LinkedIn at https:///company/statacorp,and follow Stata on Twitter at https:///stata to keep up with Stata.•Subscribe to the Stata Journal,which contains reviewed papers,regular columns,book reviews, and other material of interest to researchers applying statistics in a variety of disciplines.Visit https://.12[GSM]18Learning more about Stata•Many supplementary books about Stata are available.Visit the Stata Bookstore athttps:///bookstore/.•Take a Stata NetCourse R .NetCourse101is an excellent choice for learning about Stata.See https:///netcourse/for course information and schedules.•Attend a classroom or a web-based training course taught by StataCorp.Visithttps:///training/classroom-and-web/for course information and schedules.•View a webinar led by Stata developers.Visit https:///training/webinar/for the current list of topics and schedule.•Watch Stata videos at https:///user/statacorp.Suggested reading from the User’s Guide and reference manuals The User’s Guide is designed to be read from cover to cover.The reference manuals are designed as references to be sampled when necessary.Ideally,after reading this Getting Started manual,you should read the User’s Guide from cover to cover,but you probably want to become at least somewhat proficient in Stata right away.Here isa suggested reading list of sections from the User’s Guide and the reference manuals to help you onyour way to becoming a Stata expert.This list covers fundamental features and points you to some less obvious features that you might otherwise overlook.Basic elements of Stata[U]11Language syntax[U]12Data[U]13Functions and expressionsData management[U]6Managing memory[U]22Entering and importing data[D]import—Overview of importing data into Stata[D]append—Append datasets[D]merge—Merge datasets[D]compress—Compress data in memory[D]frames intro—Introduction to framesGraphics[G]Stata Graphics Reference ManualReproducible research[U]16Do-files[U]17Ado-files[U]13.5Accessing coefficients and standard errors[U]13.6Accessing results from Stata commands[U]21Creating reports[RPT]Dynamic documents intro—Introduction to dynamic documents[RPT]putdocx intro—Introduction to generating Office Open XML(.docx)files[RPT]putexcel—Export results to an Excelfile[RPT]putpdf intro—Introduction to generating PDFfiles[R]log—Echo copy of session tofile[GSM]18Learning more about Stata3Useful features that you might overlook[U]29Using the Internet to keep up to date[U]19Immediate commands[U]24Working with strings[U]25Working with dates and times[U]26Working with categorical data and factor variables[U]27Overview of Stata estimation commands[U]20Estimation and postestimation commands[R]estimates—Save and manipulate estimation resultsBasic statistics[R]anova—Analysis of variance and covariance[R]ci—Confidence intervals for means,proportions,and variances[R]correlate—Correlations of variables[D]egen—Extensions to generate[R]regress—Linear regression[R]predict—Obtain predictions,residuals,etc.,after estimation[R]regress postestimation—Postestimation tools for regress[R]test—Test linear hypotheses after estimation[R]summarize—Summary statistics[R]table intro—Introduction to tables of frequencies,summaries,and command results [R]tabulate oneway—One-way table of frequencies[R]tabulate twoway—Two-way table of frequencies[R]ttest—t tests(mean-comparison tests)Matrices[U]14Matrix expressions[U]18.5Scalars and matrices[M]Mata Reference ManualProgramming[U]16Do-files[U]17Ado-files[U]18Programming Stata[R]ml—Maximum likelihood estimation[P]Stata Programming Reference Manual[M]Mata Reference ManualSystem values[R]set—Overview of system parameters[P]creturn—Return c-class values4[GSM]18Learning more about StataInternet resourcesThe Stata website(https://)is a good place to get more information about Stata.You willfind answers to FAQ s,ways to interact with other users,official Stata updates,and other useful information.You can also join Statalist,a forum devoted to discussion of Stata and statistics.You will alsofind information on Stata NetCourses R ,which are interactive courses offered over the Internet that vary in length from a few weeks to eight weeks.Stata also offers in-person and web-based training sessions,as well as webinars on Stata features.Visit https:///learn/ for more 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Stata操作讲义第一讲Stata操作入门第一节概况Stata最初由美国计算机资源中心（Computer Resource Center）研制，现在为Stata公司的产品，其最新版本为7.0版。

它操作灵活、简单、易学易用，是一个非常有特色的统计分析软件，现在已越来越受到人们的重视和欢迎，并且和SAS、SPSS一起，被称为新的三大权威统计软件。

Stata最为突出的特点是短小精悍、功能强大，其最新的7.0版整个系统只有10M左右，但已经包含了全部的统计分析、数据管理和绘图等功能，尤其是他的统计分析功能极为全面，比起1G以上大小的SAS系统也毫不逊色。

另外，由于Stata在分析时是将数据全部读入内存，在计算全部完成后才和磁盘交换数据，因此运算速度极快。

由于Stata的用户群始终定位于专业统计分析人员，因此他的操作方式也别具一格，在Windows席卷天下的时代，他一直坚持使用命令行／程序操作方式，拒不推出菜单操作系统。

但是，Stata的命令语句极为简洁明快，而且在统计分析命令的设置上又非常有条理，它将相同类型的统计模型均归在同一个命令族下，而不同命令族又可以使用相同功能的选项，这使得用户学习时极易上手。

更为令人叹服的是，Stata语句在简洁的同时又拥有着极高的灵活性，用户可以充分发挥自己的聪明才智，熟练应用各种技巧，真正做到随心所欲。

除了操作方式简洁外，Stata的用户接口在其他方面也做得非常简洁，数据格式简单，分析结果输出简洁明快，易于阅读，这一切都使得Stata成为非常适合于进行统计教学的统计软件。

Stata的另一个特点是他的许多高级统计模块均是编程人员用其宏语言写成的程序文件（ADO文件），这些文件可以自行修改、添加和下载。

用户可随时到Stata网站寻找并下载最新的升级文件。

事实上，Stata的这一特点使得他始终处于统计分析方法发展的最前沿，用户几乎总是能很快找到最新统计算法的Stata程序版本，而这也使得Stata自身成了几大统计软件中升级最多、最频繁的一个。

stata 10%分位数摘要：一、引言1.了解Stata 10%分位数的重要性2.文章目的：提供Stata 10%分位数的详细操作方法二、Stata 10%分位数计算方法1.定义：将数据集按照数值大小排序2.计算：从大到小依次选取10%的样本三、操作步骤1.打开Stata软件2.输入命令：`infile`3.导入数据：`use`4.排序：`sort`5.计算10%分位数：`quantile`6.输出结果：`list`四、实例演示1.下载示例数据2.按照步骤操作，查看结果五、结果解释1.10%分位数含义：低于这个数值的样本占全体的10%2.分析结果：与均值、中位数等指标结合，全面了解数据分布六、注意事项1.数据预处理：确保数据质量，剔除异常值2.区分10%、25%、50%等分位数：各有用途，根据需求选择七、总结1.掌握Stata 10%分位数计算方法2.提高数据分析能力，为实证研究提供有力支持正文：作为一名职业写手，今天我们将为大家介绍如何在Stata软件中计算10%分位数。

分位数是一种描述数据分布状况的统计量，可以帮助我们更好地了解数据的整体情况。

在实际应用中，10%分位数常常被用来衡量数据的极端情况，以便我们更好地制定决策。

以下是计算Stata 10%分位数的详细步骤：1.打开Stata软件，进入操作界面。

2.输入命令`infile`，表示要导入文件。

接着输入文件路径，例如：`infile "D:data.dta"`。

3.导入数据。

输入命令`use`，软件会自动读取数据并显示在界面上。

4.对数据进行排序。

输入命令`sort`，数据会按照数值大小进行升序排列。

5.计算10%分位数。

输入命令`quantile`，然后按Enter键。

此时，Stata 会自动计算出10%分位数，并将其保存在变量`p10`中。

6.输出结果。

输入命令`list`，然后按Enter键。

此时，我们可以看到包含10%分位数的结果出现在界面上。