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    Names: »dprime«

└─⟦87ddcff64⟧ Bits:30001253 CPHDIST85 Tape, 1985 Autumn Conference Copenhagen
    └─⟦this⟧ »cph85dist/stat/doc/cat/dprime« 

TextFile

DPRIME(1)              UNIX User's Manual               DPRIME(1)

NAME
     dprime - compute d' and beta for signal detection data

SYNOPSIS
     dprime [hit-rate false-alarm-rate]

DESCRIPTION
     _▶08◀d_▶08◀p_▶08◀r_▶08◀i_▶08◀m_▶08◀e can be given two arguments: the hit-rate and the
     false-alarm-rate, for which it will print d' and beta.  Oth-
     erwise, _▶08◀d_▶08◀p_▶08◀r_▶08◀i_▶08◀m_▶08◀e reads raw data from the standard input.  If
     raw data are input, _▶08◀d_▶08◀p_▶08◀r_▶08◀i_▶08◀m_▶08◀e assumes a two column input in
     which the first column tells whether signal+noise or just
     noise were presented, and the second column tells how the
     observer responded.  The following strings can be used to
     indicate affirmative answers
                        signal, yes, 1, 1.0000
     while the following can be used to indicate negative:
                         noise, no, 0, 0.0000

ALGORITHM
     The value for d' is the Z value of the hit-rate minus that
     of the false-alarm-rate.
                         d' = Z(hr) - Z(far)
     This reflects the distance between the two distributions:
     signal, and signal+noise.  Though Z values can have any real
     value, normally distributed ones are between -2 and 2 about
     95% of the time, so differences of twice that would be rare.

     The value for beta is the ratio of the normal density func-
     tions of the Z values used in the computation of d'.  This
     reflects an observer's bias to say `yes' or `no' with the
     unbiased observer having a value around 1.0.  A major reason
     for doing a signal detection analysis is to get a measure of
     discrimination that is constant over observer biases, but
     the invariance of beta is often not certain.

AUTHOR
     Gary Perlman

SEE ALSO
     unixstat(1)

REFERENCE
     The chapter on Theory of Signal Detection in Coombs, Dawes,
     and Tversky's _▶08◀M_▶08◀a_▶08◀t_▶08◀h_▶08◀e_▶08◀m_▶08◀a_▶08◀t_▶08◀i_▶08◀c_▶08◀a_▶08◀l _▶08◀p_▶08◀s_▶08◀y_▶08◀c_▶08◀h_▶08◀o_▶08◀l_▶08◀o_▶08◀g_▶08◀y, 1970, Academic Press.

BUGS
     The program has not been tested extensively.

KEYWORDS
     statistics, data analysis, psychology, perception

Printed 5/30/85           March 5, 1985                         1