There are growing concerns on flow data in diverse fields including trade, migration, knowledge diffusion, disease spread, and transportation. The package is an effective visual support to learn the pattern of flow which is called halfcircle diagram. The flow between two nodes placed on the center line of a circle is represented using a half circle drawn from the origin to the destination in a clockwise direction. Through changing the order of nodes, the halfcircle diagram enables users to examine the complex relationship between bidirectional flow and each potential determinants. Furthermore, the halfmeancenter function, which calculates (un) weighted mean center of half circles, makes the comparison easier.

Build better balance in causal inference models. 'halfmoon'
    helps you assess propensity score models for balance between groups
    using metrics like standardized mean differences and visualization
    techniques like mirrored histograms. 'halfmoon' supports both
    weighting and matching techniques.

Provides methods for implementing hierarchical age length keys
    to estimate fish ages from lengths using data borrowing. Users can create
    hierarchical age length keys and use them to assign ages given length.

Conducts analyses for healthcare program evaluations or intervention 
    studies. Calculates regression analyses for standard ordinary least squares 
    (OLS or linear) or logistic models. Performs regression models used for 
    causal modeling such as differences-in-differences (DID) and interrupted 
    time series (ITS) models. Provides limited interpretations of model 
    results and a ranking of variable importance in models. Performs 
    propensity score models, top-coding of model outcome variables, and 
    can return new data with the newly formed variables. Also performs Cronbach's 
    alpha for various scale items (e.g., survey questions). See Github URL for 
    examples in the README file. For more details on the statistical methods, see 
    Allen & Yen (1979, ISBN:0-8185-0283-5), 
    Angrist & Pischke (2009, ISBN:9780691120355), 
    Harrell (2016, ISBN:978-3-319-19424-0), 
    Kline (1999, ISBN:9780415211581), and 
    Linden (2015) <doi:10.1177/1536867X1501500208>.