[visionlist] How to compute d' when hit rate or false alarm rate is 0 or 1?

Mon Jun 4 07:53:52 GMT 2007

 Hello,

If you didn't read this before, I would strongly recommend this excellent book:
Detection theory, a user's guide, by Neil A.Macmillan and C.Douglas Creelmen (Laurence Erlbaum Associates).
I am sure you will find a lot of answers, and a lot more questions!

Best regards, 
Stephane Buffat

-----E-mail d'origine-----
De : Hang Zhang <zhangh at psych.ac.cn>
A : visionlist <visionlist at visionscience.com>
Envoyé le : Dimanche 3 Jui 2007 16:03
Sujet : [visionlist] How to compute d' when hit rate or false alarm rate is 0 or 1?

Hi,

In signal detection theory, sensitivity d' is computed as the z-score difference 
between false alarm rate and hit rate. I am puzzled about what is the z-score 
for a 0 or 1 rate, because theorically the value is indefinite. But an 
indefinite d' for an observer in a psychological experiment seems 
unreasonable... Could someone tell me how to compute d' when hit rate or false 
alarm rate is 0 or 1? Many Thanks. 

Best,       
Hang

----------------------------------------------------
Hang ZHANG, PhD Candidate
State Key Laboratory of Brain and Cognitive Science
Institute of Psychology, Chinese Academy of Sciences
4A, Datun Road, Chaoyang District
Beijing 100101, China
Tel: 8610 6483 7209
Fax: 8610 6487 2070
Email: zhangh at psych.ac.cn
----------------------------------------------------

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