(a) Relevance & Research Question: Rating scales can considerably affect data quality regarding mean ratings, distribution of answers, response time, or item nonresponse (e.g., Couper, Conrad, & Tourangeau, 2007; Healey, 2007; Heerwegh & Loosveldt, 2002; Krosnick, 1999; Krosnick & Fabrigar, 1997). However, because implementation is easy, designers of Web surveys are tempted to use special rating scales without knowing much about their impact on data quality. This presentation focuses on how slider scales may harm survey data. Nevertheless, sometimes changes in rating scales are inevitable, especially when scrolling on Internet devices with an upright display (e.g., smart phones) should be avoided (for problems see Couper, Tourangeau, Conrad, & Crawford, 2004).
(b) Methods & Data: In a 2 x 2 Web experiment, type of rating scale (5-point Java-based slider versus 5-point HTML radio button scale) was manipulated as well as the spatial orientation on the screen. On a single Web page, respondents ( N = 779) had to evaluate two product concepts, counterbalanced for order. For analysis, respondents’ reported education was recoded in two groups, below college degree (e.g., B.A. or B.S.) and at least college degree.
(c) Results: Overall, break-off was significantly higher with slider scales in comparison to radio button scales, chi2(1, N = 779) = 12.81, p < .001, odds ratio = 6.92. Whereas respondents in the group with low education had problems with slider scales, chi2(1, N = 451) = 5.89, p = .018, odds ratio = 5.45, no difference in break-off was observed in the group of respondents with a high formal education, chi2(1, N = 321) = 1.66, p = 1.000. Additionally, task duration was considerably higher with slider scales, F (1, 703) = 638,23, p < .001, eta2 = .48. Furthermore, fewer respondents chose the middle category with slider scales. Spatial orientation of the rating scale had no significant influence on break-off or distribution of values.
(d) Added Value: The interaction between rating scale and educational level is a serious argument against the use of Java-based slider scales in general. Overall, it seems that horizontal and vertical layout can be substituted mutually.