Sample size and power determination

• two-sample test of equality of means
• one-sample test of means
• two-sample test of equality of proportions
• one-sample test of proportions
• repeated measurements of the outcome on each experimental unit
• Survival studies

Stepwise regression

• linear
  
• Competing risks
  
• complementary log-log
• Cox
  
• GLM
• Interval
• logistic
• conditional logistic
• negative binomial
• ordered probit
• ordered logit
• Poisson
• probit
• quantile
• Skewed logistic
  
• tobit and censored-normal
• exponential, Weibull, Gompertz lognormal, log-logistic, generalized gamma

• Wald or likelihood-ratio tests
  
• Use with survey data
  

Orthogonal polynomials

• Orthogonalize variables using modified Gram–Schmidt procedures
• Compute orthogonal polynomial for a variable  
  

Cronbach's alpha

• Interitem correlations or covariances
  
• Generate summative scale
  
• Automatically reverse sense of variables
  

Kappa measure of interrater agreement

• Two unique raters
  
• Weights for weighting disagreements
  
• Nonunique raters, variables record ratings for each rater
  
• Nonunique raters, variables record frequency of ratings
  

Kernel density estimation

• Eight different kernels
  
• Control band width
  
• Overlay normal density or Student's t density
  

• Can be applied to the left-hand side, right-hand side, or both
• Parameters can be the same or different
• Maximum likelihood
• Zero-skewness log

• Search for power transform that converts a variable into a normally distributed variable
• Graphical display of a power-transformed variable
  

Collecting statistics into a dataset 

• collect from any command
• collect results or each group or subgroup of observations
• Collection from user-written or “official” commands
  

• Shapiro–Wilk
• Shapiro–Francia**
• Skewness and kurtosis test (D’Agostino, with and without Royston correction)
• Doornik–Hansen
• Henze–Zirkler
• Two by Mardia
  

Drawing samples from multivariate normal distribution

• Default is orthogonal data
• May specify desired means and covariance or correlation matrix
• Singular covariance matrix is permitted
  
• Set random-number seed to ensure reproducibility
  

Creating datasets with specified correlation structure

• Add variables to existing dataset or create new dataset
• Singular covariance or correlation structures are permitted
• Set random-number seed to ensure reproducibility
  

Rolling and recursive analyses

• Rolling regressions
  
• Recursive regressions
  
• Reverse recursive regressions
  
• Works with almost all Stata estimation commands
  

Mathematical functions

• absolute value
• arc-cosine returning radians
• arc-sine returning radians
• arc-tangent returning radians
• two-argument arc-tangent
• sine of radians
• tangent of radians
• cosine of radians
• combinatorial function
• exponentiation
• natural logarithm
• natural log factorial
• ln(gamma(x)) (ln((x-1)!) for integer x)
• base 10 logarithm
• modulus of x with respect to y
• square root
• digamma function
• trigamma function
• Hyperbolic sine
• Hyperbolic cosine
• Hyperbolic arcsine
• Hyperbolic arccosine
  
• hyperbolic tangent
• log of odds ratio
• inverse log of odds ratio
• complementary log-log
• inverse complementary log-log
• ceiling
• floor
• minimum
• maximum
• relative difference
• running sum
• sign

Statistical functions

• Binomial probability
  
• Binomial cumulative probability
• Cumulative and inverse F distribution
  
• F density
  
• incomplete gamma
• inverse incomplete gamma
• gamma density
• incomplete beta
• noncentral beta density
• inverse binomial
• cumulative and inverse chi-squared
• inverse cumulative noncentral chi-squared
• Upper tail of cumulative beta distribution
  
• Inverse tail of cumulative beta distribution
  
• Upper tail of cumulative gamma distribution
  
• Inverse tail of cumulative gamma distribution
  
• Upper tail of right cumulative binomial
  
• cumulative noncentral chi-squared
• Dunnett's cumulative multiple range distribution*
• Inverse cumulative multiple range distribution*
  
• standard normal density
• cumulative normal
• inverse cumulative normal
• bivariate normal
• cumulative bivariate normal
• student's 2-tailed t-distribution
• t density
• inverse 2-tailed cumulative t distribution
• noncentrality parameter L for noncentral chi-squared
• first and second derivatives of gamma
• non-central F
• Hypergeometric cumulative probability
• Hypergeometric probability
• Negative binomial cumulative probability
  
• Negative binomial probability
• Negative binomial reverse cumulative probability
• Inverse cumulative negative binomial probability
• Inverse tail of cumulative negative binomial probability
  
• Poisson cumulative probability
  
• Poisson probability
• Poisson reverse cumulative probability
• Inverse cumulative Poisson probability
• Inverse tail of cumulative Poisson probability
• Tukey's cumulative Studentized range distribution*
• Inverse cumulative Studentized range distribution*