
	XTAB
	----

	THE FORTRAN PROGRAM XTAB HAS ALL THE ESSENTIAL FEATURES OF THE
	"XTAB" COMMAND IN THE PROGRAM CROSS BUT OPERATES ON USER-ENTERED
	CONTINGENCY TABLES INSTEAD OF READING DATA FROM A FILE.


      PROGRAM XTAB

      DESCRIPTION
	THIS PROGRAM CROSS-TABULATES PAIRS OF VARIABLES (WITH OR WITHOUT
	A CONTROL VARIABLE) GIVING FREQUENCIES, PERCENTAGES, OR OTHER
	STATISTICS DESIRED BY THE USER.

      SOURCE
	NORMAN W. JOHNSON, DEPARTMENT OF MATHEMATICS, WHEATON COLLEGE,
	NORTON, MASS.

      INSTRUCTIONS
	THE USER MAY ENTER OR ANALYZE DATA BY GIVING ONE OF THE COMMANDS
	"INPUT", "OUTPUT", OR "ZERO" OR MAY TERMINATE THE EXECUTION OF
	THE PROGRAM BY TYPING "STOP".

	THE COMMAND "INPUT" (OPTIONALLY FOLLOWED BY THE TABLE SIZE) EN-
	ABLES THE USER TO ENTER A HYPOTHETICAL FREQUENCY TABLE FOR TWO
	OR THREE VARIABLES TO BE CROSS-TABULATED.  ONE OR MORE OUTPUT
	OPTIONS MUST BE SELECTED AND THE APPROPRIATE CODE NUMBERS EN-
	TERED.  THE FOLLOWING OPTIONS ARE AVAILABLE:

		1--FREQUENCY OF RESPONSES
		2--PERCENTAGES ACROSS
		3--PERCENTAGES DOWN
		4--PERCENTAGES OF TOTAL
		5--CHI-SQUARE, DEGREES OF FREEDOM, AND PROBABILITY
		6--GOODMAN AND KRUSKAL'S TAU
		7--YULE'S Q OR GOODMAN AND KRUSKAL'S GAMMA
		8--PHI COEFFICIENT OR KENDALL'S TAU
		9--SOMER'S D

	THE COMMAND "OUTPUT" PERMITS THE USER TO KEEP THE DATA OF THE
	LAST CROSS-TABULATION BUT TO CHANGE THE OUTPUT OPTIONS.

	THE COMMAND "ZERO", GIVEN AFTER A CROSS-TABULATION INVOLVING A
	CONTROL VARIABLE, PRODUCES THE CORRESPONDING ZERO-ORDER STATIS-
	TICS.

	AFTER ANY OF THE ABOVE COMMANDS IS CARRIED OUT, A NEW COMMAND
	MAY BE GIVEN.  THE USER MAY SUPPRESS THE PRINTING OF TABLES OR
	ANY OTHER OUTPUT IN ORDER TO GIVE A NEW COMMAND IMMEDIATELY BY
	TYPING <CTRL>O AND PRESSING <RETURN>.  FURTHER EXECUTION OF A
	COMMAND MAY BE HALTED AT ANY BREAK POINT BY TYPING "ABORT".

	WHENEVER THE USER IS EXPECTED TO GIVE A COMMAND OR TO PROVIDE
	CERTAIN INFORMATION NEEDED FOR THE EXECUTION OF A COMMAND, AN
	EXPLANATION OF WHAT IS REQUIRED MAY BE OBTAINED BY TYPING THE
	WORD "EXPLAIN" OR SIMPLY A QUESTION MARK.

	THIS PROGRAM ASSUMES THAT OUTPUT IS TO THE USER TERMINAL.  IF
	OUTPUT TO A FILE ON THE DISK IS DESIRED INSTEAD, THE DISK SHOULD
	BE ASSIGNED LOGICAL UNIT 5 PRIOR TO RUNTIME.

      REMARKS
	THE COMPUTED VALUE OF CHI-SQUARE WITH ONE DEGREE OF FREEDOM
	INCORPORATES A CORRECTION FOR CONTINUITY.  THE CALCULATION OF
	CHI-SQUARE IS ACCOMPANIED BY A WARNING IF THE EXPECTED FREQUENCY
	IS LESS THAN 1 IN ANY CELL OR LESS THAN 5 IN MORE THAN 20 PER
	CENT OF THE CELLS.  KENDALL'S TAU HAS A CORRECTION FOR TIES.

      REFERENCES
	JAMES A. DAVIS, 'ELEMENTARY SURVEY ANALYSIS', PRENTICE-HALL,
	    ENGLEWOOD CLIFFS, N.J., 1971.
	JOHAN GALTUNG, 'THEORY AND METHODS OF SOCIAL RESEARCH', COLUMBIA
	    UNIVERSITY PRESS, NEW YORK, 1967.
	E. TERRENCE JONES, 'CONDUCTING POLITICAL RESEARCH', HARPER &
	    ROW, NEW YORK, 1971.

