1 My thinking in this area benefits from discussions with my colleagues Constance Malpas and Brian Lavoie over the last few years. A final draft of this paper was improved by suggestions by Constance Malpas.
2 This section draws on my contributions to Bell, Dempsey and Fister (2015)
3 This section is based on Dempsey (2016).
4 This section is based on Dempsey (2015b).