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 logit
• Ordered probit
• Poisson
• Probit
• Quantile
• Skewed logistic
• Tobit
• Exponential, Weibull, Gompertz, lognormal, loglogistic, generalized gamma

Nested-model statistics

• 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

Box–Cox transform

• 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

Power transforms

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

Tests of normality

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

Collecting statistics into a dataset

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

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
• Arccosine returning radians
• Arcsine returning radians
• Arctangent returning radians
• Two-argument arctangent
• 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 cumulative probability
• Binomial 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
• Noncentral 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