Sod turfgrass provides significant environmental benefits (Beard and Green, 1994; Stier et al., 2013). However, if improperly managed or used in drought-prone areas, sod causes detrimental environmental effects, such as high water consumption or excessive nutrient and pesticide runoff (Beard and Green, 1994; Stier et al., 2013). Consumers who prefer specific sod attributes maintain large swaths of irrigated and managed turf areas (Ghimire et al., 2016, 2019; Yue et al., 2017). To address some of the tough management issues and meet consumer demand, sod producers may seek to adopt new varieties. Developing and marketing new low-input sod varieties is one way to reduce the environmental effects of sod production and management by the public.
As the sod industry expands, producers and breeders face the challenge of producing new and improved varieties to meet consumer demand at reasonable prices (Chung et al., 2018). While prior studies identified household consumer preferences for sod varieties (Ghimire et al., 2016, 2019; Hugie et al., 2012; Yue et al., 2012, 2017), little information is available on what products sod producers believe they can market to consumers. Given that producers may only be able to grow and market limited varieties at a time, knowing what the producers perceive as valuable is also important for the development and ultimate adoption of improved sod varieties for the consumer market. Unlike previous studies that evaluate consumer (or homeowner) preferences, our study focuses on evaluating sod producers’ preferences for biotic stress improvements and maintenance reductions of new warm-season varieties.
Discrete choice experiments (DCEs) are widely used to help reveal how respondents value each attribute or characteristic of a product, in the form of a consumer’s willingness-to-pay (WTP) or a producer’s willingness-to-accept (WTA). To identify producers’ preferences for sod attributes, we conduct a DCE in combination with the eye-tracking technology. The eye-trackers contribute real-time data for the individual’s attendance and fixation to each attribute. In the theory of DCE, each respondent is assumed to evaluate and process all information provided during each choice task efficiently, thus making consistent choices with a constant degree of variability (Day et al., 2012; Hensher et al., 2005). The attribute non-attendance (ANA) problem arises when respondents do not pay attention to all attributes in all alternatives in the choice experiment. Previous studies confirmed the existence of ANA, which may lead to inconsistent decisions and biased preference estimates, typically represented by WTP or WTA (Hensher et al., 2005; Kragt, 2013).
The extent of eye-fixation could affect the likelihood of an alternative being chosen and therefore, estimates of respondents’ preferences for product and service attributes (Behe et al., 2015; Bialkova et al., 2014; van der Laan et al., 2015), as well as the estimated WTP, in an unpredictable direction (Rihn and Yue, 2016). Respondents’ eye-fixation may also reveal the learning and fatigue effects when they face multiple choice-tasks (Balcombe et al., 2015). When respondents learn across choice tasks, they make decisions that are more consistent and exhibit lower variances; when participants are fatigued or bored, their decisions are more inconsistent, thus exhibiting higher variances. By investigating the consistency of variance scales in the logit function, we can identify respondents’ learning or fatigue effects.
The overall objective of this study is to estimate sod producers’ preferences for warm-season sod attributes. We also demonstrate the importance of addressing the ANA problem and attentional changes using eye-tracking data. Besides, we identify possible learning and fatigue effects by considering the effect of eye fixations. Finally, we discuss discrepancies between producers’ WTA estimates and consumers’ WTP estimates previously reported by Ghimire et al. (2019). Our study allows us to signal sod producers’ preferences for production and sale of warm-season turf-varieties in sod firm (rather than seed). As the sod producer group is small and can be hard to reach, having information about their production preferences and how they evaluate different attributes compared with consumers is a significant contribution to the sod industry.
Our study results show that respondents ignore some of the attributes, as some respondents identified as visual non-attenders even ignored specific attribute(s) in more than half of the 12 choice tasks. Price was the most ignored attribute. Our respondents value drought tolerance the most, followed by shade tolerance, winterkill reduction, salinity tolerance, and lastly, a 10% maintenance cost reduction. Based on the statistical tests, there was no clear evidence showing that respondents’ preferences vary with their attention change, even though we identified an overall learning effect along sequential choices. We also found that in general, producers’ WTAs were higher than consumers’ WTPs for the improved sod attributes, except for the drought tolerance attribute. However, the rankings for all attributes were the same between consumers and sod producers, indicating that sod producers understand the consumer preferences of their household market to some extent.
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