╘EST OR SURVEY RESULTS OFTEN CONSIST OF MASSES OF NFORMATION. ╔N ORDER TO MAKE SOME SENSE OF THE DATA IT PAYS TO TABULATE THE RESULTS INTO MEANINGFUL SIZE GROUPS. ╘HIS IS NORMALLY DONE BEFORE STATISTICAL TESTS ARE APPLIED, AS DATA INSPECTION CAN POINT US IN THE DIRECTION OF PICKING THE APPROPRIATE TESTS. ╘ABULATING DATA IS A TRIVIAL AND EASY TASK, BUT ERROR PRONE. ├OMPUTER TO THE RESCUE: FAST AND ACCURATE.
╧NE METHOD OF TABULATION IS HISTOGRAMS, ALSO CALLED BAR-CHARTS, WHICH LOOK LIKE THIS:
Ç*FP8
╨┼╧╨╠┼
5! *
4! * *
3! * *
2! * * * *
1! * * * * *
0+-/-+-----+-----+-----+-----+-----╘┼╙╘
<=50 61-70 71-80 81-90 >90 ╙├╧╥┼╙
╘HIS PROGRAM DOES NOT ACTUALLY DRAW HISTOGRAMS, BUT IT GROUPS DATA INTO INTERVALS THAT CAN BE SO GRAPHED. ╔T DISPLAYS THE UPPER AND LOWER LIMITS OF EACH INTERVAL, THE FREQUENCY COUNT IN THE INTERVAL, AND THE CUMULATIVE TOTAL. ┘OU CAN USE THE DATA TO DRAW A HISTOGRAM.
// PRG: TAB //
Ç*FP14
*** ╓┴╥╔┴┬╠┼╙ ***
─╓ OUTPUT DEVICE, SCREEN OR PRINTER
╬ NUMBER OF VALUES TO SCAN
╓() TABLE OF VALUES TO BE SCANNED
╬╔ NUMBER OF INTERVALS
╫╠,╫─ WIDTH OF NUMBERS THAT PRINT
╥ RANGE OF NUMBERS
╙┌ INTERVAL SIZE BASED ON ╥
╠,╚ LOW AND HIGH BOUNDRIES OF EACH INTERVAL
╠╓ INTERVAL NUMBER
╙╠ NUMBER OF ITEMS IN THE INTERVAL
╙╙ TOTAL UP TO THAT POINT (CUMULATES ╙╠-S)
┴┴ WORKING VALUE, STARTING POINT
Ç*FP3
*** ╔╬╙╘╥╒├╘╔╧╬╙ ***
╧NE REQUIREMENT FOR APPLICATIONS OTHER THAN THIS SIMPLE DEMO: THIS PROGRAM NEEDS THE DATA TO HAVE BEEN PRESORTED PREVIOUSLY.
╥╒╬ THE PROGRAM. ╔T STOPS BY ITSELF WHEN THE COMPUTER FINISHES GROUPING A TEST SET OF NUMBERS.
*** ─┼╘┴╔╠╙ ***
╫E SIMULATE A TABLE OF DATA IN SORTED ORDER BY CREATING A TABLE OF VALUES EACH LARGER THAN THE PREVIOUS ONE. ╔N FACT, EACH VALUE IS A SUM OF THE PREVIOUS VALUES PLUS ITSELF WHICH GUARANTEES THAT THE VALUES ARE IN INCREASING ORDER.
╧UR ARTIFICIAL TABLE IS BUILT IN LINES 120-140. ╘HEN WE ASK THE SUBROUTINE IN LINES 9040-9130 TO DIVIDE THE DATA INTO ╬╔=10 INTERVALS. ╘HE COMPUTER TRACKS DOWN THE DATA BY COMPARING THE VALUES WITH THE UPPER AND LOWER BOUNDS OF THE INTERVALS WHICH IT FIRST CALCULATES IN LINE 9050.
╘HE SCREEN SHOWS THE RESULTS: THE INTERVAL BOUNDS AND THE FREQUENCY COUNT. ╘HEY ARE UNTITLED, TO SAVE YOU TYPING, BUT IT SHOULD BE OBVIOUS WHICH IS WHICH.
// PIC: TAB //
╘HIS ROUTINE RUNS ON ANY ├OMMODORE COMPUTER. ╔T USES AN OLD-FASHIONED METHOD OF PRINTING NUMERIC RESULTS: TAKING A CHARACTER STRING OF A VALUE AND PADDING IT ON THE LEFT WITH BLANKS.
╫HEN YOU ASK FOR A SPECIFIC NUMBER OF INTERVALS, SOMETIMES THE RESULTS WILL LOOK FUNNY - THERE MAY BE NO ENTRIES IN MOST OF THEM, AND LOTS IN OTHERS. ┬Y PLAYING WITH THE ORIGINAL VALUES AND THE INTERVAL SIZE, YOU CAN ZOOM IN ON THE BEST DATA REPRESENTATION THAT FITS YOUR NEEDS.
*** ╨╥╧╩┼├╘╙ ***
╨LOT THE DATA INTO A HISTOGRAM, THIS CAN BE DONE BY PRINTING STARS ACCROSS THE SCREEN.
╨LOT HIGH-RESOLUTION DIAGRAMS OF EACH INTERVAL AND LABEL THEM.
╔NSTEAD OF USING PRECOOKED VALUES FOR SAMPLE DATA, USE ─┴╘┴ LINES WITH OTHER KINDS OF NUMBERS. ┘OU COULD SORT THEM YOURSELF USING THE PREVIOUS SORT ROUTINE.
╥EWRITE THE PROGRAM WITH ╨╥╔╬╘ ╒╙╔╬╟ FOR A NEAT LOOKING OUTPUT IN ORDER TO REPLACE THE CURRENT STRING HANDLING TECHNIQUE.
