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# CITATION.cff file created with {cffr} R package
# See also: https://docs.ropensci.org/cffr/
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cff-version: 1.2.0
message: 'To cite package "iop" in publications use:'
type: software
license: GPL-3.0-only
title: 'iop: Inflated Ordered Probit and Logit Models'
version: 0.1.0
identifiers:
- type: doi
  value: 10.32614/CRAN.package.iop
abstract: 'Estimation, inference, and quantities of interest for ordered probit and
  ordered logit models whose outcome contains an inflated category: a single ordered
  category (bottom, middle, top, or any other) that mixes observations generated by
  the ordered process with observations generated by a distinct split-population process.
  Fits the zero-inflated ordered probit of Harris and Zhao (2007) <https://doi.org/10.1016/j.jeconom.2007.01.002>
  and its middle- and top-inflated extensions (Bagozzi and Mukherjee 2012 <https://doi.org/10.1093/pan/mps020>;
  Bagozzi, Hill, Moore and Mukherjee 2015 <https://doi.org/10.1177/0022002713520530>;
  Bagozzi, Joo and Mukherjee 2024 <https://doi.org/10.1093/fpa/orae006>), generalized
  to an arbitrary inflated category and to the logit link, with optional correlated
  errors for the probit form, plus the standard ordered probit and logit and their
  partial proportional-odds (non-parallel) variants on the same footing. Provides
  analytic, robust, and cluster-robust standard errors, survey weights and offsets,
  model comparison (Vuong, likelihood-ratio, information criteria), regime-specific
  predicted probabilities and first differences, simulation for residual diagnostics,
  and tidy/table-package integration. The likelihood, its gradient, and the bivariate-normal
  probabilities are implemented in C++.'
authors:
- family-names: Bagozzi
  given-names: Benjamin E.
  email: bagozzib@udel.edu
preferred-citation:
  type: manual
  title: 'iop: Inflated Ordered Probit and Logit Models'
  authors:
  - family-names: Bagozzi
    given-names: Benjamin E.
    email: bagozzib@udel.edu
  year: '2026'
  notes: R package version 0.1.0
  url: https://github.com/bagozzib/iop
repository: https://bagozzib.r-universe.dev
repository-code: https://github.com/bagozzib/iop
commit: c0f0039b7c1782d82cf527fbc1dffc7852f3aba2
url: https://bagozzib.github.io/iop/
date-released: '2026-09-03'
contact:
- family-names: Bagozzi
  given-names: Benjamin E.
  email: bagozzib@udel.edu
references:
- type: article
  title: A mixture model for middle category inflation in ordered survey responses
  authors:
  - family-names: Bagozzi
    given-names: Benjamin E.
  - family-names: Mukherjee
    given-names: Bumba
  journal: Political Analysis
  year: '2012'
  volume: '20'
  issue: '3'
  doi: 10.1093/pan/mps020
  start: '369'
  end: '386'
- type: article
  title: 'Modeling two types of peace: The zero-inflated ordered probit (ZiOP) model
    in conflict research'
  authors:
  - family-names: Bagozzi
    given-names: Benjamin E.
  - family-names: Hill
    given-names: Daniel W.
  - family-names: Moore
    given-names: Will H.
  - family-names: Mukherjee
    given-names: Bumba
  journal: Journal of Conflict Resolution
  year: '2015'
  volume: '59'
  issue: '4'
  doi: 10.1177/0022002713520530
  start: '728'
  end: '752'
- type: article
  title: Top-category inflation in ordered international relations outcomes
  authors:
  - family-names: Bagozzi
    given-names: Benjamin E.
  - family-names: Joo
    given-names: Minnie M.
  - family-names: Mukherjee
    given-names: Bumba
  journal: Foreign Policy Analysis
  year: '2024'
  volume: '20'
  issue: '2'
  doi: 10.1093/fpa/orae006
  start: orae006