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# sure: Surrogate Residuals <img src="tools/sure-logo.png" align="right" />

An R package for constructing **SU**rrogate-based **RE**siduals and diagnostics for ordinal and general regression models; based on the approach described in [Dungang and Zhang (2017)](http://www.tandfonline.com/doi/abs/10.1080/01621459.2017.1292915?journalCode=uasa20).


## Installation

The `sure` package is [currently listed on CRAN](https://CRAN.R-project.org/package=sure) and can easily be installed:
```r
# Install from CRAN (recommended)
install.packages("sure")
  
# Alternatively, install the development version from GitHub
if (!requireNamespace("devtools")) install.packages("devtools")
devtools::install_github("AFIT-R/sure")
```


## References

Liu, Dungang and Zhang, Heping. Residuals and Diagnostics for Ordinal Regression Models: A Surrogate Approach.
*Journal of the American Statistical Association* (accepted). URL
http://www.tandfonline.com/doi/abs/10.1080/01621459.2017.1292915?journalCode=uasa20
