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Debunking the Monday Irrationality through the External Affection of Investors

Gadjah Mada International Journal of Business (GamaIJB) · Vol. 18 No. 1 (2016) · pp. 83–105

DOI
10.22146/gamaijb.9293
ISSN
2338-7238, 1411-1128
Published
2016-02-19
Publisher
Master in Management, Faculty of Economics and Business, Universitas Gadjah Mada
Language
eng
License
creativecommons.org/licenses/by-sa/4.0

Abstract

This study aims to reveal the mechanism of the influences of the full moon and high temperatures on investors’ Monday irrationality. In contrast to other studies, this research was built under a retroductive approach by using a time series quasi experimental study. Investors were directly assessed for their irrationality by using an adapted psychometric test on 4 occasions. The results indicate that there were indeed effects of the full moon and high temperatures on investors’ irrationality. Because the full moon and high temperatures frequently occurred on Mondays, it is most probably those two variables that were the drivers of the Monday irrationality. In the end, we concluded that the rational behaviour assumption can no longer be held. Instead of rationality, the investors were quasi rational. The utility function of Von Neumann-Morgenstern in decision making has to be replaced by the hedonic utility.

Keywords

Collaboration network of the authors

7 authors · 9 co-authorship links · 7 across different organisations

Hover or tap a name to highlight its co-authors. Double-click to open the author's page.

  • Universiti Sains Malaysia
  • Universiti Malaysia Sarawak
  • Petra Christian University
  • Tunku Abdul Rahman University of Management and Technology
  • Medan Area University
  • Different organisations
  • Same organisation
  • Affiliation unknown
  • Thicker line = more joint articles · bigger circle = more articles
Show as table
Co-authorOrganisationJoint articles
Ritzky Karina BrahmanaPetra Christian University1
Theresa Char Fei HoTunku Abdul Rahman University of Management and Technology1
Abdul Hadi ZulkafliUniversiti Sains Malaysia1
Eky Ermal MMedan Area University1

Affiliations come from OpenAlex; journal OAI-PMH metadata carries none. Authors without an OpenAlex ID are matched by name, which can merge or split people.

Metadata source: OAI-PMH (metadata jurnal) https://journal.ugm.ac.id/gamaijb/oai, first harvested 28 Okt 2026, last seen 28 Okt 2026.
Original metadata (oai_dc) 
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	<dc:title xml:lang="en-US">Debunking the Monday Irrationality through the External Affection of Investors</dc:title>
	<dc:creator>Brahmana, Rayenda</dc:creator>
	<dc:creator>Hooy, Chee-Wooi</dc:creator>
	<dc:creator>Ahmad, Zamri</dc:creator>
	<dc:subject xml:lang="en-US"></dc:subject>
	<dc:subject xml:lang="en-US">C93, G02, G19, O16</dc:subject>
	<dc:description xml:lang="en-US">This study aims to reveal the mechanism of the influences of the full moon and high temperatures on investors’ Monday irrationality. In contrast to other studies, this research was built under a retroductive approach by using a time series quasi experimental study. Investors were directly assessed for their irrationality by using an adapted psychometric test on 4 occasions. The results indicate that there were indeed effects of the full moon and high temperatures on investors’ irrationality. Because the full moon and high temperatures frequently occurred on Mondays, it is most probably those two variables that were the drivers of the Monday irrationality. In the end, we concluded that the rational behaviour assumption can no longer be held. Instead of rationality, the investors were quasi rational. The utility function of Von Neumann-Morgenstern in decision making has to be replaced by the hedonic utility.</dc:description>
	<dc:publisher xml:lang="en-US">Master in Management, Faculty of Economics and Business, Universitas Gadjah Mada</dc:publisher>
	<dc:contributor xml:lang="en-US"></dc:contributor>
	<dc:date>2016-02-19</dc:date>
	<dc:type>info:eu-repo/semantics/article</dc:type>
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	<dc:type xml:lang="en-US">Peer-reviewed Article</dc:type>
	<dc:format>application/pdf</dc:format>
	<dc:identifier>https://journal.ugm.ac.id/gamaijb/article/view/9293</dc:identifier>
	<dc:identifier>10.22146/gamaijb.9293</dc:identifier>
	<dc:source xml:lang="en-US">Gadjah Mada International Journal of Business; Vol 18, No 1 (2016): January-April; 83-105</dc:source>
	<dc:source>2338-7238</dc:source>
	<dc:source>1411-1128</dc:source>
	<dc:language>eng</dc:language>
	<dc:relation>https://journal.ugm.ac.id/gamaijb/article/view/9293/6894</dc:relation>
	<dc:rights xml:lang="en-US">Copyright (c) 2016 Gadjah Mada International Journal of Business</dc:rights>
	<dc:rights xml:lang="en-US">http://creativecommons.org/licenses/by-sa/4.0</dc:rights>
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