เปรียบเทียบวิธี

	มาตรวัดความตั้งใจซื้อสินค้าสีเขียว	มาตรวัดอัตลักษณ์ทางสิ่งแวดล้อม
สาขาวิชา	จิตวิทยาสิ่งแวดล้อม	จิตวิทยาสิ่งแวดล้อม
ตระกูล	Process / pipeline	Process / pipeline
ปีกำเนิด	1991	2003
ผู้ริเริ่ม	William B. Dodds, Kent Monroe, Dhruv Grewal	Susan D. Clayton
ประเภท	Self-report intention and willingness-to-pay scale	Self-report identity and self-concept scale
แหล่งต้นตำรับ	Dodds, W. B., Monroe, K. B., & Grewal, D. (1991). Effects of price, brand, and store information on buyers' product evaluations. Journal of Marketing Research, 28(3), 307–319.	Clayton, S. D. (2003). Environmental identity: A conceptual and an operational definition. In S. D. Clayton & S. Opotow (Eds.), Identity and the natural environment: The psychological significance of nature (pp. 45–65). MIT Press.
ชื่อเรียกอื่น	GPIS, Eco-Friendly Purchase Intention	EIS, Ecological Identity Scale
ที่เกี่ยวข้อง	3	4
สรุป	The Green Purchase Intention Scale (GPIS) measures consumers' stated willingness and likelihood of purchasing environmentally friendly products, including their intention to pay premium prices for eco-labeled goods and their perceived value of sustainable alternatives. Developed from consumer behavior and willingness-to-pay frameworks (Dodds, Monroe, & Grewal, 1991; expanded by Thøgersen and others), the GPIS bridges environmental attitudes and actual purchasing behavior, a critical gap in sustainability research. The scale is widely used in marketing research, environmental policy evaluation, and studies examining whether environmental concern translates into purchasing decisions.	The Environmental Identity Scale (EIS) measures the degree to which individuals incorporate environmental values and ecological concerns into their sense of self—how central environmental stewardship is to personal identity and self-concept. Developed by Clayton (2003) from identity theory and social psychology, the EIS captures environmental identity as a psychological construct distinct from attitudes, values, or behaviors alone. High EIS scores indicate that individuals view themselves as 'environmental people' for whom conservation and sustainability are integral to who they are. The scale is foundational for research on sustainable behavior motivation, examining why environmental values persist and translate into behavior for some individuals but not others, and evaluating whether environmental interventions shift identity and thus self-motivated behavior change.