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Stata Frequently Asked Questions

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• How can I convert files among SAS, SPSS and Stata?
• How do I export Stata .dta files to other programs?
• How do I export Stata .dta files to a SAS Xport file?
• How can I load, write, or view a dBASE file, Excel file or Access file using odbc?
• How can I convert a Stata file to an MLwiN file using Stata program stata2mlwin?
• How can I convert a Stata file to an Mplus file?
• Stata to HLM
  • Easiest: How do I convert a Stata file to HLM?
  • Harder: How can I convert a Stata file to an HLM file using HLM Windows interface?
  • Harder: How to separate a Stata single file into multiple data files for analysis in HLM software?
• How can I input a dataset quickly?
• How do I read a data file that uses commas/tabs as delimeters?
• How can I output a formatted ASCII file?
• How do I load large data sets (> 1GB) under 32-bit Windows? (from Stata FAQs)

• How do I make windows dock, pin, and float? (shown as a movie)
• How do I load window settings? (shown as a movie)
• How do I save window settings? (shown as a movie)
• How do I set other window preferences? (shown as a movie)
• How do I change the font (PC version)?

• How can I create all pairs within groups?
• How do I copy Stata output and Stata graphs into Word?
• How can I save the contents of the results window?
• How can I make the results window hold more results?
• How do I update my copy of Stata?
• I have Stata 10, how can I save data so they can be used in Stata 8 or 9?
• How do I check that the same data input by two people are consistently entered?
• How can I list observations in blocks?
• Can I do by and sort in one command?
• Why am I losing precision with large whole numbers (such as an ID variable)?  
• How can I quickly recode continuous variables into groups?
• How do I standardize variables (make them have a mean of 0 and sd of 1)?
• How can I merge multiple files in Stata?
• How can I combine a large number of files?
• How can I randomly assign observations to groups in Stata?
• How can I draw a random sample of my data?
• How can I "fill down"/expand observations with respect to dates and then update my dates?
• How do I assign the values of one variable as the value labels for another variable?
• How can I detect duplicate observations?
• How can I access information stored after I run a command in Stata (returned results)?
• How can I identify cases used by an estimation command using e(sample)?
• Missing values
  • Can I quickly see how many missing values a variable has?
  • How can I see the number of missing values and patterns of missing values in my data file?
  • How can I quickly recode missing values into different categories?
• String variables
  • How can I quickly convert many string variables to numeric variables?
  • How can I turn a string variable containing dates into a date variable Stata can recognize?
  • How can I extract a portion of a string variable using regular expressions?

• How can I handle the matsize too small error?
• How can I handle the No Room to Add Observations error?

• How do I do this SAS Command in Stata?
• How do I do this SPSS Command in Stata?

• How can I compute power for contingency tables in Stata?
• How can I get descriptive statistics and the five number summary on one line?
• Why do I get different values of kurtosis in SAS, Stata and SPSS?
• What are the differences between one-tailed and two-tailed tests?

• Interactions and comparing coefficients across groups
  • How can I understand a 3-way continuous interaction? Part 1, Part 2
  • How can I understand a continuous by continuous interaction?
  • How can I understand a categorical by continuous interaction?
  • How can I get anova main-effects with dummy coding?
  • How can I compare regression coefficients between 2 groups?
  • How can I compare regression coefficients across 3 (or more) groups?
• Regression graphics
  • How can graphically compare OLS and BLUP results in Stata?
  • How can I do a scatterplot with regression line in Stata?
• Types of regression
  • How can I get an R² with robust regression (rreg)?
  • How do I interpret quantile regression coefficients?
  • How does one do regression when the dependent variable is a proportion?
  • What is seemingly unrelated regression and how can I perform it in Stata?
  • How can I analyze count data in Stata?
  • How can I use countfit in choosing a count model?
  • How does xtreg-re differ from xtreg-fe?
• How can I compute effect size in Stata for regression?
• Comparing various methods of analyzing clustered data in Stata.
• How can I create dummy variables in Stata?
• Can I make regression tables that look like those in journal articles?
• How can I analyze multiple mediators in Stata?
• How can I do moderated mediation in Stata?
• How can I perform Sobel-Goodman mediation tests?
• How can I run a piecewise regression in Stata?
• How can I find where to split a piecewise regression?
• How can I perform the likelihood ratio, Wald, and Lagrange multiplier (score) test in Stata?
• How Can I Perform Post Estimation Tests with Multiply Imputed Datasets?

• How can I understand a categorical by continuous interaction in logistic regression?
• How can I understand a categorical by categorical interaction in logistic regression?
• How do I interpret odds ratios in logistic regression?
• How do I use adjust in probit or logit?
• How can I get a Somers' D after logistic regression in Stata?
• How can I estimate relative risk using glm for common outcomes in cohort studies?
• How can I test the difference in area under ROC curve for two Logistic Models?

• How can I understand a three-way interaction in ANOVA?
• How can I determine the correct term in an ANOVA using Stata?
• How can I get anova main-effects with dummy coding?
• How can I get anova simple main effects with dummy coding?
• How can I compute critical values for test of simple effects?
• How can I compute effects size after anova?
• How can I do classical ANOVA designs using xtmixed?
• How can I do post-hoc pairwise comparisons in Stata?
• How can I do post-hoc pairwise comparisons of adjusted means in Stata?
• How can I do profile analysis in Stata?
• How can I do multivariate repeated measures in Stata?
• How can I plot ANOVA cell means in Stata?
• How can graph group means and standard deviations for ANOVA?
• How can I do ANOVA contrasts in Stata?
• How can I do tests of simple main effects in Stata?
• How can I check for homogeneity of variance in a factorial ANOVA design?
• How can I test for nonadditivity in a randomized block ANOVA in Stata?
• How does the ANOVA command handle collinearity? (from Stata FAQs)

• How can I graph chi-square power curves in Stata?
• Where can I find examples of user written graph commands for Stata?
• How can I do a profile plot in Stata?
• How can graph group means and standard deviations for ANOVA?
• How can I plot ANOVA cell means in Stata?
• How can I combine a histogram and a boxplot in Stata?
• How can I make a bar graph with error bars?
• How can I use postgr3 to make graphs of predicted values after an estimation command?
• How can I graph two (or more) groups using different symbols?
• How do I graph data with dates?
• How can I view/compare different marker symbol options?
• How do I save a Stata graph as an EPS file?
• How do I use version 7 graph commands in later versions of Stata ?
• How do I use xtline in Stata?
• How can I visualize longitudinal data in Stata?

• How to collapse a daily time series to a monthly time series
• How to extract month and year component from a variable with %tm format

• See the Stata capabilities page for information about the capabilities of Stata, including Linear models, Binary, count, and limited dependent variables, Resampling and simulation methods, Graphics, Survey methods, Survival analysis

• How do I use the Stata survey (svy) commands?
• Sample setups for commonly used survey data sets
• Choosing the correct analysis for various survey designs
• How can I check for collinearity in survey regression?
• How can I do a t-test with survey data?
• How can the standard errors with the cluster() option be smaller than those without the cluster() option? (from Stata FAQs)
• Do the svy commands handle zero weights differently than non-svy commands? (from Stata FAQs)
• How can I analyze a subpopulation of my survey data in Stata?
• Why doesn't summarize accept pweights? What does summarize calculate when you use aweights? (from Stata FAQs)

• How can I convert a multilevel model to a mixed model?
• How can I do correspondence analysis on summary data?
• How to do parallel analysis for pca or factor analysis in Stata?
• How can I compute tetrachoric correlations?
• How can I calculate a kappa statistic for variables with unequal score ranges?
• Testing the proportional hazard assumption in Cox models
• How should I analyze percentile rank data?
• Why doesn't summarize accept pweights? What does summarize calculate when you use aweights? (from Stata FAQs)
• Why do estimation commands sometimes drop variables?  (from Stata FAQs)
• How can I test for equality of distribution?
• How can I test for a trend across a categorical variable?
• How do I write my own bootstrap program?
• How can I manually generate the predicted counts from a ZIP or ZINB model based on the parameter estimates?
• How can I perform multiple imputation on longitudinal data using ICE?
• How can I calculate Moran's I in Stata?
• How do I generate a variogram for spatial data in Stata?
• How can I fit a random intercept or mixed effects model with heteroskedastic errors in Stata?

• What is the difference between = and == in STATA?
• What types of weights do SAS, Stata and SPSS support?
• How do I do elementwise operations on a matrix?
• How can I get poisson probabilities in Stata?
• How can I generate a saturated model using DESMAT?
• How can I translate a file into a Postscript file?
• How do I use file write to write results or other information to an external text file?
• How do I use file read to read in information in an external text file?
• How do I use findit to search for programs and additional help?

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