Taylor Swift is Type O+

According to Answers.com and other sources, Taylor Swift is Type O+.

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Warren Buffett is O!

According to Answers.com Warren Buffett is O.

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Steve Jobs is Type O-

I find his blood type on Japanese Wikipedia!
It is type O, Rh minus.
For some reason, there is no blood type information on English Wikipedia.
Why?

The following is another source.

For your information, Time Cook, Apple's present CEO is O-, too.

Interesting study by Prof. Hideo Hirose: Human Intuition Can Guess Blood Type

Here is an interesting study by Mr. Hideo Hirose, Professor at the Kyushu Institute of Technology (now he is at the Hiroshima Institute of Technology), in which person's ABO blood types can be guessed intuitively.

Source: Hirose Lab.

Hideo Hirose, A Probabilistic Solution for the Mystery of Japanese Blood Type Prediction Accuracy (2015) Asian Conference on Psychology & the Behavioral Sciences 2015 Official Conference Proceedings. -> Source (PDF)

We have revealed that people implicitly use the underlying knowledge of relationship between personality and ABO blood types as imprinting, which shows us superficial human intuition ability.

Multivariate Covariance Analysis (MANCOVA) Textbook

There was nothing good in Japanese, so I asked for an English version of the book.

Patrick Dattalo, Analysis of Multiple Dependent Variables

Ah, this book seems to be quite tough to read.
I hope it doesn't become a sleeping pill (laughs).