INTRODUCTION Straightlining, or identical responses across all items within a multi-item scale, is often taken as an indication that responses to all items in a questionnaire are of poor quality. The purpose of this study was to examine straightlining on two scales: The Sense of Unity Scale (SUS) and the short version of the Warwick-Edinburgh Mental Well-being Scale (SWEMWBS). METHODS Data stem from the 2017-2018 data collections in four Nordic countries of the Health Behaviour in School-children study (HBSC) (15-year-old students only; 50.9% girls; n = 5928). Data were weighted to adjust for oversampling of Swedish-speaking Finnish students and to equalize sample size across countries. The main analyses were done with general linear modeling with adjustments for cluster effects (school classes). RESULTS The proportion with straightlining on SUS was 22.8%, varying from 5.8% among Swedish girls to 46.4% among Finnish boys. The proportion with straightlining on SWEMWBS was 18.4%, varying from 5.2% among Norwegian girls to 46.0% among Finnish boys. Straightlining on one of the scales correlated with straightlining on the other one. Straightlining tended to inflate Cronbach's α values and reduce number of factors in factor analyses. Associations between the two scales and external variables tended to be lower among straightlining students. Associations between external variables (other than SUS/SWEMWBS) are on average slightly weaker among straightliners. Straightlining students obtained more favorable scores on several resource-related variables. CONCLUSION Although some problems have been identified, straightlining does not serve well as a general indicator of poor data quality.

中文翻译：

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北欧青少年在无聊的环境中应对苛刻的调查量表：检查直线。

引言 多项目量表中所有项目的直线或相同的回答通常被视为对问卷中所有项目的回答质量较差的指示。本研究的目的是在两个量表上检查直线：统一感量表 (SUS) 和沃里克-爱丁堡心理健康量表 (SWMWBS) 的简短版本。方法 数据来源于 2017-2018 年在四个北欧国家收集的学童健康行为研究 (HBSC)（仅限 15 岁学生；50.9% 的女孩；n = 5928）。对数据进行加权以调整对讲瑞典语的芬兰学生的过度抽样，并使各国的样本量相等。主要分析是通过对集群效应（学校班级）进行调整的一般线性模型进行的。结果 SUS 的比例为 22.8%，从瑞典女孩的 5.8% 到芬兰男孩的 46.4% 不等。在 SWEMWBS 上直线的比例为 18.4%，从挪威女孩的 5.2% 到芬兰男孩的 46.0% 不等。其中一个尺度上的直线与另一尺度上的直线相关。直线趋于夸大 Cronbach 的 α 值并减少因子分析中的因子数量。在直线学生中，两个量表和外部变量之间的关联往往较低。外部变量（除了 SUS/SWWEMWBS）之间的关联在直线型中平均略弱。直线型学生在几个与资源相关的变量上获得了更有利的分数。结论 尽管已经发现了一些问题，