Panel-data ERMs
Extended regression models (ERMs) were a big new feature last release. The ERM commands fit models that account for three common problems that arise in observational data—endogenous covariates, sample selection, and treatment—either alone or in combination.
In Stata 16, we introduce the xteregress, xteintreg, xteprobit, and xteoprobit commands for fitting panel-data ERMs. This means ERMs can now account for the three problems we mentioned above and for within-panel correlation. These new commands fit random-effects linear, interval, probit, and ordered probit regression models. They allow random effects in one or all equations, and they allow random effects to be correlated across equations.
Researchers from all disciplines who work with observational (nonexperimental) data are interested in ERMs and will be excited about the new panel-data versions of these commands. However, different disciplines talk about these models differently.
Above, we referred to the problems ERMs solve as endogenous covariates, sample selection, treatment, and within-panel correlation. While this terminology is common in some disciplines such as economics, other disciplines may use other terms.
• Instead of panel-data and within-panel correlation, researchers may ask for models for multilevel (two-level) data that account for within-group correlation.
• Instead of endogenous covariates, researchers may ask for methods of dealing with unobserved confounding or unmeasured confounding.
• Instead of sample selection, researchers may be concerned about trials with informative dropout, nonignorable nonresponse, or outcomes missing not at random (MNAR).
• Instead of treatment, researchers may ask about methods for causal inference or estimating average treatment effects (ATEs).
The important message is that all disciplines are interested in ERMs, but they often speak different languages.
Stata是一款完整的、集成的统计软件包，提供您需要的一切数据分析、数据管理和图形。
快速,简单并易于使用
点击式的界面和强大,直观的命令语言让Stata使用起来快速,精确并易于使用。
所有的分析结果都可以被复制和存档，并用来出版和审查。不管您什么时候写的内容，版本控制系统确保统计程序可继续生成同样的结果。
Stata的作图模块，主要提供如下八种基本图形的制作 : 直方图（histogram），条形图（bar），百分条图 （oneway），百分圆图（pie），散点图（two way），散点图矩阵（matrix），星形图（star），分位数图。这些图形的巧妙应用，可以满足绝大多数用户的统计作图要求。在有些非绘图命令中，也提供了专门绘制某种图形的功能，如在生存分析中，提供了绘制生存曲线图，回归分析中提供了残差图等。
Stata的矩阵运算功能
矩阵代数是多元统计分析的重要工具， Stata提供了多元统计分析中所需的矩阵基本运算，如矩阵的加、积、逆、 Cholesky分解、 Kronecker内积等；还提供了一些高级运算，如特征根、特征向量、奇异值分解等；在执行完某些统计分析命令后，还提供了一些系统矩阵，如估计系数向量、估计系数的协方差矩阵等。
统计功能
Stata使得大量的统计工具用于指尖
标准方法，如
基本表格和总结
案例对照分析
ARIMA
ANOVA 和MANOVA
线性回归
时间序列平滑
广义线性模型（GLM）
聚类分析
对比和比较
功率分析
样本选择
……
高级方法，如
多层模型
生存分析
动态面板数据回归
结构方程建模
二进制，计数和审查结果
ARCH
多重替代法
调查数据
Treatment effects
精确统计
贝叶斯分析
……
值得信任
技术支持
我们不仅编写统计方法，我们还会进行验证。
您能从Stata estimator rest与其他估计的比较中看到Monte-Carlo模拟的一致性和覆盖率以及我们统计学家们进行的广
泛测试。每一版的Stata软件，我们都通过了各种认证，包括230万行的代码测试，并产生了430万行的结果输出。我们验
证了这430万行代码中的每一个数字和每一段文字。
Stata 16 New in Bayesian analysis—Multiple chains, predictions, and more
Multiple chains.
Bayesian inference based on an MCMC (Markov chain Monte Carlo) sample is valid only if the Markov chain has converged. One way we can evaluate this convergence is to simulate and compare multiple chains.
The new nchains() option can be used with both the bayes: prefix and the bayesmh command. For instance, you type
. bayes, nchains(4): regress y x1 x2
and four chains will be produced. The chains will be combined to produce a more accurate final result. Before interpreting the result, however, you can compare the chains graphically to evaluate convergence. You can also evaluate convergence using the Gelman–Rubin convergence diagnostic that is now reported by bayes: regress and other Bayesian estimation commands when multiple chains are simulated. When you are concerned about noncovergence, you can investigate further using the bayesstats grubin command to obtain individual Gelman–Rubin diagnostics for each parameter in your model.
Bayesian predictions.
Bayesian predictions are simulated values from the posterior predictive distribution. These predictions are useful for checking model fit and for predicting out-of-sample observations. After you fit a model with bayesmh, you can use bayespredict to compute these simulated values or functions of them and save those in a new Stata dataset. For instance, you can type
. bayespredict (ymin:@min({_ysim})) (ymax:@max({_ysim})), saving(yminmax)
to compute minimums and maximums of the simulated values. You can then use other postestimation commands such as bayesgraph to obtain summaries of the predictions.
The dataset created by bayespredict may include thousands of simulated values for each observation in your dataset. Sometimes, you do not need all of these individual values. To instead obtain posterior summaries such as posterior means or medians, you can use bayespredict, pmean or bayespredict, pmedian. Alternatively, you may be interested in a random sample of the simulated values. You can use, for instance, bayesreps, nreps(100) to obtain 100 replicates.
Finally, you may want to evaluate model goodness of fit using posterior predictive p-values, also known as PPPs or as Bayesian predictive p-values. PPPs measure agreement between observed and replicated data and can be computed using the new bayesstats ppvalues command. For instance, using our earlier example
. bayesstats ppvalues {ymin} {ymax} using yminmax
Stata 16 Feature highlights：
1. Lasso
2. Reporting
3. Meta-analysis
4. Choice models
5. Python integration
6. New in Bayesian analysis—Multiple chains, predictions, and more
7. Panel-data ERMs
8. Import data from SAS and SPSS
9. Nonparametric series regression
10. Multiple datasets in memory
11. Sample-size analysis for confidence intervals
12. Nonlinear DSGE models
13. Multiple-group IRT models
14. xtheckman
15. Multiple-dose pharmacokinetic modeling
16. Heteroskedastic ordered probit models
17. Graph sizes in printer points, centimeters, and inches
18. Numerical integration
19. Linear programming
20. Stata in Korean
21. Mac interface now supports Dark Mode and native tabbed windows
22. Do-file Editor—Autocompletion and more syntax highlighting
In Stata 16, we introduce a new, unified suite of commands for modeling choice data. We have added new commands for summarizing choice data. We renamed and improved existing commands for fitting choice models. We even added a new command for fitting mixed logit models for panel data. And we document them together in the new Choice Models Reference Manual.
And here’s the best part: margins now works after fitting choice models. This means you can now easily interpret the results of your choice models. While the coefficients estimated in choice models are often almost uninterpretable, margins allows you to ask and answer very specific questions based on your results. Say that you are modeling choice of transportation. You can answer questions such as
• What proportion of travelers are expected to choose air travel?
• How does the probability of traveling by car change for each additional $10,000 in income?
• If wait times at the airport increase by 30 minutes, how does this affect the choice of each mode of transportation?
What else is new? You now cmset your data before fitting a choice model. For instance,
. cmset personid transportmethod
Then, you use cmsummarize, cmchoiceset, cmtab, and cmsample to explore, summarize, and look for potential problems in your data.
And you use cm estimation commands to fit one of the following choice models:
• cmclogit conditional logit (McFadden’s choice) model
• cmmixlogit mixed logit model
• cmxtmixlogit panel-data mixed logit model
• cmmprobit multinomial probit model
• cmroprobit rank-ordered probit model
• cmrologit rank-ordered logit model
Unlike the others, cmxtmixlogit is not just renamed and improved. It is completely new in Stata 16, and
Stata 是一套提供其使用者数据分析、数据管理以及绘制专业图表的完整及整合性统计软件。它提供许许多多功能，包含线性混合模型、均衡重复反复及多项式普罗比模式。用Stata绘制的统计图形相当精美。
新版本的STATA采用较具亲和力的窗口接口，使用者自行建立程序时，软件能提供具有直接命令式的语法。Stata提供完整的使用手册，包含统计样本建立、解释、模型与语法、文献等**过一万余页的出版品。
除此之外，Stata软件可以透过网络实时更新每天的较新功能，更可以得知世界各地的使用者对于STATA公司提出的问题与解决之道。使用者也可以透过Stata Journal获得许许多多的相关讯息以及书籍介绍等。另外一个获取庞大资源的管道就是Statalist，它是一个独立的listserver，每月交替提供使用者**过1000个讯息以及50个程序。
Stata的统计功能很强，除了传统的统计分析方法外，还收集了近20年发展起来的新方法，如Cox比例风险回归，指数与Weibull回归，多类结果与有序结果的logistic回归，Poisson回归，负二项回归及广义负二项回归，随机效应模型等。具体说， Stata具有如下统计分析能力：
数值变量资料的一般分析：参数估计，t检验，单因素和多因素的方差分析，协方差分析，交互效应模型，平衡和非平衡设计，嵌套设计，随机效应，多个均数的两两比较，缺项数据的处理，方差齐性检验，正态性检验，变量变换等。
分类资料的一般分析：参数估计，列联表分析 ( 列联系数，确切概率 ) ，流行病学表格分析等。
等级资料的一般分析：秩变换，秩和检验，秩相关等
相关与回归分析：简单相关，偏相关，典型相关，以及多达数十种的回归分析方法，如多元线性回归，逐步回归，加权回归，稳键回归，二阶段回归，百分位数 ( 中位数 ) 回归，残差分析、强影响点分析，曲线拟合，随机效应的线性回归模型等。
其他方法：质量控制，整群抽样的设计效率，诊断试验评价，kappa等。
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不管您是需要购买单款软件，还是制定整个实验室的购买方案，都可以提供。
Sample-size analysis for confidence intervals in Stata 16
The new ciwidth command performs Precision and Sample Size (PrSS) analysis, which is sample-size analysis for confidence intervals (CIs). This method is used when you are planning a study and you want to optimally allocate resources when CIs are to be used for inference. Said differently, you use this method when you want to estimate the sample size required to achieve the desired precision of a CI in a planned study.
ciwidth produces sample sizes, precision, and more that are required for the
• CI for one mean
• CI for one variance
• CI for two independent means
• CI for two paired means
The control panel interface lets you select the analysis type and input assumptions to obtain desired results.
ciwidth allows results to be displayed in customizable tables and graphs.
ciwidth also provides facilities for you to add your own methods.
出版质量的图形
Stata轻松生成出版质量、风格迥异的图形。您可以编写脚本并以可复制的方式生成成百上千个图形，并且可以以EPS
或TIF格式输出打印、以PNG格式或SVG格式输出放到网上、或PDF格式输出预览。使用这个图形编辑器可更改图形的任何
方面，或添加标题、注释、横线、箭头和文本。
问：Stata 有没有一些培训或者教程？
答：科学软件网提供stata的视频课程，目前有些课程是**免费的。另外每年都会提供stata线上线下的一些培训，有兴趣可以去 科学软件网 上查看。
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