The Result varies from questionnaire to questionnaire of the relation between blood type and personality. Also difference appears in some cases and it does not appear in other cases. It continued to confuse researchers. However, I may have unravelled the mystery, if my reasoning is correct. There is clear and consistent relation between blood type and personality. I am not a boy Kandaichi (a famous Japanese comic and animation detective), but I think I manage to unravel the mistery. :-) Have a fun!
"Opponents" in Japan pointed out the following problems to "admit" the relation between blood type and personality.
1. There is not reliability of data, because random sampling is not carried out.
2. Even if the difference appears, there is not any reappearance of data because trend differs by questionnaire.
3. Even if the difference appears, it do not necessarily agree the personality of each blood type.
I can say "there are relation" if I solve three above problems.
I tried original reasoning. I think it is about 80 points
(= passing mark) in self grading. How is it?
Conditions like the following are necessary for stable results.
1. Homogeneous subjects (social position, age, region etc.)
2. The number of subjects is more than several hundred (more than one thousand and ratio of each blood types are the same, if possible)
3. Choose the personality description of Mr. NOMI.
4. Results does not correspond to Mr. NOMI's description ("language" does not represent "personality") -- also affected by culture and country etc.
I will explain in order.
The difference of personality by blood type is small than expected. It is only about 10 to 20 % at most, although it depends on contents of a question. Moreover, there are many factors that affect the difference: age, area, sex distinction, social position etc. -- even the same blood type. Therefore, the difference does not appear when "random sampling" is done. One should not choose "random sampling" method, a popular method of psychology.
On the contrary, the clear difference appears, when I see data of university students. There is few differences such as age, region, social position -- namely homogeneous.
As I write above, The difference of personality by blood type is small than expected -- It is only about 10 to 20 % at most. Therfore, more than several hundreds subjects (over 1,000, if possible) are needed when one wants to get significant difference(s) in a usual statistical method (chi-square test). In this case, if the same number of each blood-type subjects are chosen, the difference becomes easy to appear. You can understand right away if you calculate. I omitt the method of concrete calculation here because it becomes long.
This is easy. Because difference is difficult to appear in usual personality tests (such as Yatabe-Gilford Personality Test in Japan). Question items "somehow" can not measure the difference by blood type. I don't know the reason. Cattell's 16 Personality Factor Inventory is an exception.
As I write above, the difference of personality by blood type is affected by many factors: age, area, sex distinction, social position etc. As Mr. NOMI says, the word regarding a personality is not necessarily expressing it. For example, Type O becomes reliant, when put to a weak position, although it fundamentally independent. Type B replied s/he is most "independent" when I saw the data of Mr. Omura's university students. Therefore, the result didn't surprise me. Difference always appears, if there is relation between blood type and personality anyway.
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Last update: December 31, 1997.