producers and researchers to consider when and how phone surveys should be used in the future; when and for what purposes it is advantageous to employ phone surveys either to replace (parts of) in-person data collection or to complement it; how integration or supplementation of in-person and phone surveys should be conducted and what are the best practices for doing so.

In this paper, we review experiences with phone surveys in low- and middle-income countries against the conceptual framework provided by the Total Survey Error (TSE) paradigm (Biemer, 2010; Groves and Lyberg, 2010), drawing implications for the design and implementation of future survey practice. While there is a substantial amount of literature on the topic for high-income countries, particularly the US (AAPOR, 2010; Lavrakas et al., 2017; Groves et al., 1988) and Europe (Jäckle, Roberts and Lynn, 2006; Häder, Häder, and Kühne, 2012; Lynn and Kaminska, 2013; Villar and Fitzgerald, 2017), the trajectory in the adoption and diffusion of survey modes in those countries has been quite different than it is in many low-income countries. Landlines in the US and Europe were at one point nearly universal and are now being complemented and partially supplanted by mobile phone and web connections. Therefore, while the experience accumulated in the US and Europe is very relevant, many of the issues that matter to survey practitioners appear with several different features and nuances in low-income settings, particularly in rural areas.<sup>2</sup> Against this backdrop and drawing on an extensive review of the literature and analysis of primary data, we conclude that there is great potential for the combination of phone and in-person surveys for agricultural data collection. To reach that conclusion our review takes into consideration the specific constraints around using phones for agricultural and rural surveys, including the nature of the questions, abbreviated interview duration, and the need for post-survey adjustments to account for uneven mobile phone coverage, as well as the advantages of phone surveys, namely the flexibility to schedule interviews appropriately around the agricultural season and the reduced costs and simplified logistics compared to in-person interviews.

The paper is organized as follows. In Section 2, we present the conceptual framework (based on the TSE paradigm) and adapt it to evaluate the role phone surveys can play in agricultural and rural survey systems in the coming years. We also introduce the phone survey programs and experiences on which we draw throughout this review. In Section 3 we discuss issues of coverage and nonresponse bias that emerge when designing and implementing phone surveys on agriculture, focusing on sampling and representativeness (3.1), respondent selection (3.2), and post-survey adjustments (3.3). Section 4 discusses issues of measurement including questionnaire design and survey timing (4.1), the role of the respondent (4.2), and the role of the interviewer (4.3). Section 5 discusses cost considerations. We conclude in Section 6.

> 2 The literature in high-income countries distinguishes at times between fixed and mobile phone surveys. In lowincome settings, and particularly in rural areas, mobile phones are by far the most prevalent. In what follows, we therefore just use the term phone survey, having in mind that in most instances the means of contact will be a mobile phone.

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