COMMISSION D'ETUDES I                               Contribution tardive)
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	                                                   Contribucion tardia )
       STUDY GROUP I AND ITS WORKING PARTIES      Texte disponible seulement en)
       COMISION	DE ESTUDIO I                      Text available only in
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       Geneve, 28 mai -	7 juin 1991

       Question: 28/I

       SOURCE: AT&T

       TITLE: Performance, Preference, and Usage for Q and Z on
       10-Digit	Keypads

       1.  Introduction

       Ten-key pads are	used world-wide	for telephones,	Automatic
       Teller Banking Machines (ATMs), and Point of Sale terminals
       (POSs). Both CCITT and ISO subcommittees	are currently
       considering standardization of the placement of Latin
       letters on 10-key pads.	To date, CCITT SGI,
       ISO/IEC/JTC1/SC17, and ISO/IEC/JTC1/SC18/WG9 have agreed
       that a common international standard should affirm the
       placement of the	24 letters as they currently appear on
       telephones, ATMs, and POSs.  This telephone layout is
       illustrated in Figure 1a.  However, the letters Q and Z do
       not currently appear on telephones, and there has been much
       recent discussion of where they should appear on	10-key pads
       in an International Standard.  The two possibilities that
       have received the most consideration to date have been 1)
       placement of Q and Z on the 1 key (Q/Z=1) and 2)	placement
       of Q on the 7 key and Z on the 9	key in alphabetic order.
       These assignments are illustrated in Figures 1b and 1c.

       This contribution summarizes results of two studies
       conducted to determine if there are usage, preference, or
       performance differences that would support one of these
       arrangements over the other: A laboratory study examined
       performance and preference. A national preference and usage
       study among active ATM and calling card users collected

				  - 2 -

       information on PIN usage	and on preferences for the two

       The following summarizes	the design of the studies and their
       main results.

       2.  Laboratory_Study

       Subjects	keyed in letter	strings	on DTMF	telephone keypads
       using each of the two mapping schemes.  Three keypads were
       used in the study, as illustrated in Figures 1a-c. Half of
       the subjects used standard phones without Q and Z marked	on
       the keys.  The others used telephones modified to include Q
       and Z on	the keypad, half the time using	the Q/Z=1
       arrangement, half the time the Q=7/Z=9 arrangement.

       A total of 64 people participated in this study.	Each
       subject dialed names, 800 "vanity" numbers, and four-letter
       passwords.  There were 32 strings of each type, and half	of
       the strings of each type	contained the letters Q	or Z.  The
       letter strings to be keyed in were presented one	at a time
       in large	letters	on a computer monitor.	Presentation of
       lists and mapping schemes were appropriately

       2.1  Results

       Both performance	and preference data were collected.
       Performance was measured	by the number of errors	subjects
       made in keying a	letter string and by the amount	of time	it
       took to enter the letters. Preference ratings were collected
       after subjects used each	mapping	scheme,	as well	as after
       the experiment.

       Errors An error was recorded whenever the digits	dialed did
       not exactly correspond to the letter string presented to	the
       subject.	 In addition, any time a subject paused	longer than
       5 seconds between digits, that trial was	recorded as an

       Table 1 shows the errors	for the	two mapping schemes for
       marked and unmarked phones. The results show no
       statistically significant differences in	errors made with
       the two mapping schemes.1

				  - 3 -

		Table 1.  Number and Percentages of Errors
		  |   Marked Phones|   Unmarked	Phone|
		  | Q/Z=1|  Q=7/Z=9|  Q/Z=1|  Q=7/Z=9|
		  |   134|     133 |	156|	 130 |
		  |   17%|     17% |	20%|	 17% |

       Keying Time Total keying	time was calculated by adding the
       times from first	to last	keypress and the time from stimulus
       presentation to first keypress.	Only correctly keyed
       strings were included in	the timing data.  Table	2 shows	the
       mean keying time	in seconds for the two QZ mapping schemes
       for the marked and unmarked telephones.	Users keyed
       slightly	faster on marked phones	with the Q=7/Z=9 mapping,
       but on the unmarked phones using	the Q/Z=1 mapping.  The
       differences found here are small	(on the	order of half a
       second or less) compared	to the average time it takes to	key
       in a string (11.7 seconds).

	Table 2.  Means	and SDs	for Total Keying Time (in Seconds)
	       |	 Marked	Phones |  Unmarked Phones|
	       |	Q/Z=1	Q=7/Z=9|  Q/Z=1	  Q=7/Z=9|
	       | Mean|	12.0	 11.3  |  11.5	   12.0	 |
	       | SD  |	 2.8	  2.2  |   1.6	    2.7	 |

       Preference Ratings At the end of	the experiment,	subjects
       were asked which	of the QZ mapping schemes they preferred.
       Table 3 shows the number	of subjects preferring each

       Overall,	significantly more of the subjects preferred the
       Q=7/Z=9 arrangement (61%	vs 39%).2


	1. By a	chi square test, X squared = 0.88, p = .35.

	1. Binomial test, p =.05.

				  - 4 -

	     Table 3.  User Preference for QZ Mapping Scheme
		  |   Marked Phones|   Unmarked	Phone|
		  | Q/Z=1|  Q=7/Z=9|  Q/Z=1|  Q=7/Z=9|
		  |   12 |     20  |	13 |	 19  |
		  |   38%|     63% |	41%|	 59% |

       3.  Field_Study

       The objectives of this study were to:

	  o Assess peoples' preferences	for the	two Q/Z	mapping
	    schemes and	the reasons for	their preferences.

	  o Assess the incidence of choosing personal
	    identification numbers (PINs) based	on letters and
	    numbers, and of mapping assigned numeric PINs to

	  o Assess the incidence of dialing letters on telephones
	    and	ATMs as	well as	awareness of various situations
	    involving alphabetic entry from 10-key pads.

	  o Understand how people currently choose PINs.

       3.1  Design

       Mall intercept interviews were conducted	with 400 people	in
       four national regions.  Two hundred interviews were
       conducted with ATM cardholders and the same number with
       telephone calling card users.  To ensure	familiarity with
       PINs and	calling	card use, only respondents who reported	at
       least weekly use	of either card were included in	the study.

       Interview protocols began with basic screening questions.
       Respondents were	then shown one of two otherwise	identical
       telephones that differed	only in	the placement of the
       letters Q and Z and asked to dial a small set of	names, PINs
       and alphabetical	telephone numbers using	the dialpad.  They
       then rated the telephone	overall	and on several specific
       dimensions. Similar use and ratings of a	telephone with the
       other Q/Z placement, and	then ratings comparing the two
       telephone layouts, followed. One-half of	the participants
       saw each	of the two layouts first. Further questions
       assessed	card usage, PIN	selection, awareness of	alphabetic
       dialing situations, actual alphabetic dialing usage, and
       demographic variables.

				  - 5 -

       3.2  Results

       Preferred Mapping Scheme	Overall, respondents preferred the
       Q=7/Z=9 letter placement	over the QZ=1 placement, by 83%	to
       17%.  This preference for the alphabetical order	mapping
       scheme was stable across	individual ratings for each
       telephone; comparative ratings after experience with both
       telephone alphabetical layouts; component ratings of the	two
       layouts for ease	of letter entry, speed of dialing letters,
       and accuracy of dialing letters;	and for	simple direct
       preference judgments.

       Reasons for Preference and Comments Of those respondents	who
       preferred the alphabetical order	layout (N=331),	81%
       mentioned basing	this preference	on something to	do with
       alphabetical order, particularly	that Q and Z are easier	to
       find when they appear in	their logically	ordered	positions.
       Of those	who preferred the Q/Z on 1 layout (N=67),
       legibility and ease of finding Q	and Z with them	on the 1
       key were	the two	most common reasons for	preference.
       Spontaneous comments by respondents on the Q/Z=1	layout
       indicated that 25% found	it hard	to find	Q and Z	and 18%
       couldn't	find Q at all.

       Incidence of Dialing Letters Awareness and usage	of dialing
       letters on telephone dials and ATM pads was high	for this
       sample of respondents.  Two-thirds of the sample	said they
       had ever	dialed letters on a telephone, and 62% do so at
       least once a month.  One-third of the ATM users report ever
       entering	letters	from an	ATM 10-key pad.	Between	one-half
       and one-quarter of the respondents were familiar	with
       alphabetical entry for 800 telephone numbers, bank card
       PINs, or	calling	card PINs.

       Incidence of Choosing/Assigning PINs with Letters
       Respondents were	asked to provide generic information about
       their current ATM and/or	calling	card PINs.  Approximately
       20% of calling card owners have chosen their own	PIN; nearly
       64% of ATM card owners have chosen their	own PIN.  One-third
       of the ATM card owners who have chosen their own	PINs chose
       an alphabetic PIN.  This	means that about 20% of	ATM card
       owners chose aphabetical	PINs.  For calling card	owners,
       this number is about 6%.	Interestingly, approximately 13% of
       those who use an	assigned numeric PIN use a word	or letters
       to remember it. Very few	people would be	affected by either
       placement of Q/Z	on 10-key pads in terms	of the embedded
       base of alphabetical PINs.  One-percent of the entire sample
       of active card users reports having a Q or Z in their PIN.

				  - 6 -

       4.  Summary

       The purpose of the studies reported here	was to determine if
       people's	performance in keying in strings of letters and/or
       their current usage or preferences provide a basis for
       choosing	between	the Q/Z=1 and Q=7/Z=9 10-digit keypad
       letter-mapping arrangements.  The performance results
       (errors and keying time)	did not	provide	a basis	for
       choosing	one arrangement	over the other.	 Preference
       results,	however, support the choice of the Q=7/Z=9

       Performance measures - errors and keying	time - showed only
       small differences between the two alternatives.