A recent BBC story addresses the Japanese custom linking character to blood type, otherwise known as Ketsueki-gata. Rob Bailey, psychologist and Principal Consultant, Research and Development at OPP discusses the drawbacks of relying on such a system.
As with many non-scientific based personality analyses, Ketsueki-gata rings alarm bells with psychologists like myself. While within the psychometrics industry we also claim to be able to make accurate predictions about people’s personalities and characteristics, we use very different methods. A key difference between us and practitioners of pseudoscience is that we continually collect data to check that our methods actually work. Graphologists, Astrologists and blood type enthusiasts don’t tend to collect data – they rely on anecdotes and magical thinking to hoodwink people into accepting the veracity of their ludicrous claims.
The popularity of Ketsueki-gata in Japan means that a person’s blood type is believed to determine temperament and personality. ‘What’s your blood type?’ is often a key question in everything from matchmaking to job applications. Many research studies have contradicted these beliefs citing scientific errors, such as including no quantitative data, violating statistical rules, having flawed methodologies and presenting inconsistent results; all contributing to the evidence that no connection exists between a person’s blood type and personality.
Psychometrics makes accurate predictions of behaviour and potential, based on decades of research and application. Persona Bubble is based on the ‘Big Five’ model of personality. It identifies five broad dimensions of personality – a widely accepted model that has influenced the development of many other trait-based assessments.
So before employers or potential partners consider asking for a date’s blood type or a candidate’s blood type during an interview (which, in itself, could result in an uncomfortable situation), perhaps look into a more scientifically proven method of assessing personality type – such as PersonaBubble’s free personality test.
The graph below shows the clear difference between proven methods and the preserve of the charlatan.
Key for the graph, which is from Robertston and Smith (2001)
A validity index of 1 would show a perfect fit between the assessment method and what it is predicting; 0 shows no relationship; 0.4 and above is very respectable