Point Biserial Correlation                                       (STB-17: sg20)
--------------------------

	^pbis^ bvar cvar [^if^ exp] [^in^ range]

performs a point biserial correlation and tests whether the correlation
coefficient is significantly different from zero.  ^pbis^ is used when
correlating a dichotomous variable with a continuous variable.  The point
biserial correlation coefficient is a true Pearson product-moment
correlation and therefore the same assumptions apply.  When using ^pbis^,
^bvar^ must be in the form of a zero/one dichotomous variable.  The
results displayed after employing ^pbis^ include ^Np^, ^Nq^, ^p^, and ^q^
(the number of observations and respective ratios determined by the
dichotomous variable).  

System macros made available include the following:

	^S_1^	Point biserial coefficient
	^S_2^	t-ratio
	^S_3^	Total number of observations
	^S_4^	^Np^ or number of observations for ^bvar^==1 
	^S_5^	^Nq^ or number of observations for ^bvar^==0
	^S_6^	Mean of ^cvar^
	^S_7^	Variance of ^cvar^


Author
------
          John A. Anderson, Manager of Operations
          Local Technical Assistance Program
          Pennsylvania Transportation Institute
          The Pennsylvania State University
          FAX   717-948-6031
          EMAIL jaa5@@psuvm.psu.edu


Also see
--------

    STB:  sg20 (STB-17)
On-line:  ^help^ for ^pbis^
