(a) 



FIGURE 6. 



(b) 



(c) 



(d) 



(a) THE REGRESSION LINE IS A "LINE SEGMENT" THAT EXTENDS 

 OVER THE DEPTH INTERVAL OF POINTS IN ITS LINE SET, BUT NOT 

 OVER THE DEPTHS OF NEIGHBORING POINTS, (b) NEIGHBORING 

 LINE SEGMENTS MEET IN THE "RANGE OF OVERLAP" TO FORM A 

 "UNION." THE POINT AT WHICH THEY MEET IS CALLED A 

 "REGRESSION POINT." (c) NEIGHBORING LINE SEGMENTS DO 

 NOT MEET IN THE RANGE OF OVERLAP. IF THE LINE SEGMENTS 

 ARE EXTENDED tO THE POINT OF INTERSECTION (d) THEN AT 

 LEAST ONE DATA POINT (IN THIS INSTANCE, POINT C) WILL 

 NOT BE WITHIN HALF A STYLUS THICKNESS OF THE RESULTING 

 UNION. 



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