Supplement 4

Mr. Kanazawa cross-checked blood-typical 28 question items of two surveys conducted by Japanese psychologists (Ms. Yoriko Watanabe and Mr. Shigeyuki Yamaoka *1). 

Mr. Yamaoka said that 15 answers showed statistical significance with much blood-typical knowledge subjects of 649 persons (total number of questions is 28, as mentioned).  On the contrary, no answer showed statistical significance with little blood-typical knowledge subjects of 651 persons.  Many psychologists thought these differences were caused by "blood-typical beliefs" (conformation bias and/or self-fulfilling phenomenon) so that the relationship of blood types and personalities is not real.

Strangely enough, 7 questions out of those significant 15 ones are "wrong" answers.  For example, scores of type O people are sometimes higher than A people, even if questions are originally for type "A" -- not O.  Wondering, Mr. Kanazawa investigated the phenomenon carefully.

If the relationship of blood types and personality is imaginary (i. e. caused by blood-typical briefs), scores of statistical differences must be proportional to those of trait (blood-typical personality) recognition (Chart A; dots are actual data and a line shows the trend). On the contrary, if the relationship is real, scores of statistical differences have nothing to do with those of trait recongnition (Chart B).

The results are as indicated by dots and a line below (Chart C).

In reality, almost no relationship was observed. As a matter of fact, the correlation coefficient is minus 0.10!

If there are any positive relations, the coefficient of correlation must be plus!

This result suggests that the relationship of blood type and personality is real, not imaginary.

*1 Shigeyuki Yamaoka (2001), A Psychology Book for not to Become a Useless Adult

山岡重行 ダメな大人にならないための心理学

28 Question Items

Type A Items

• Polite
• Introvert, solve problem by oneself * (wrong answer: AB is highest)
• Cooperative *
• Considerate, careful about everything *
• Responsible
• Esteem principle than practice
• Emotional and sensitive

Type B Items

• Shaken easily * (wrong answer: A is highest)
• Warm hearted
• Have many friends, frank and sociable
• Less influenced by the surroundings with going-my-way style *
• Optimistic *
• Lack of prudence *
• Active and curious * (wrong answer: O is highest)

Type AB Items

• Avoid close human relations * (wrong answer: B is highest)
• Prudent and kind
• Fairy-tale like *
• Rational thinking
• Cool and dry
• Capricious * (wrong answer: B is highest)
• Moody and sometimes seem dual personality *

Type O Items

• Pleasant personality
• Positive and a person of action
• Demonstrate maximum courage and willpower for a purpose *
• Strong willed
• Straight expressions and desires * (wrong answer: B is highest)
• Individualistic and sometimes self-centered * (wrong answer: B is highest)
• Passionate

*Statistically significant