@device(postscript)
@make[article, form 1]

@style(indent 0, topmargin 1 in)
@style(references=1nAPA)
@style(widowaction=force, orphanaction=force)
@style(fontfamily helvetica, size 10)
@style(spacing 2)

@skip[1]
@pageheading(left "Rule Use with the Information Lens",
             center "", 
             right "Mackay et al")
@pagefooting(center "@value(page)")

@begin[heading,size 16]
How Do Experienced Information Lens Users Use Rules?
@end[heading]

@skip[2]
@begin(center,size=10,facecode b)
Wendy E. Mackay, Thomas W. Malone, Kevin Crowston, David Rosenblitt
@i[Massachusetts Institute of Technology]

Stuart K. Card, Ramana Rao
@i[Xerox Palo Alto Research Center]
@end(center)

@skip[4]
@center{@subheading[Abstract]}
@skip[1]

The Information Lens provides electronic mail users with the ability to
write rules that automatically process their messages. This paper
describes preliminary results from a nine-month investigation of the use
of Lens.  We report the experiences of 13 voluntary users who have each
had three or more months of experience with the final version of the
software.

We are interested in the following questions.  What kinds of rules prove
useful after several months of experience with the system?  Can
non-programmers use Lens effectively?  What are the conditions under
which people delete rules?  When do people choose to run their rules?
How do people's predictions of how they use Lens match what they actually
do?  We found that: @skip[1]

@begin[itemize]
Rules based on distribution lists are most common (54%).  A
surprising number of rules (31%) look at the subject of a message.

Most users create rules that identify messages addressed to them 
personally.

Users do not use deletion rules capriciously and are more likely to 
create complex, highly-qualified delete rules than complex move rules.

One third of the users choose to only run rules before reading mail, one
third run rules only after reading mail and one third run rules both
before and after reading mail.

Non-programmers write fewer rules than programmers but are equally likely
to report satisfaction with the system.

Users do not always predict accurately which rules will prove 
most useful to them. 
@end[itemize]

@skip[2]
@center[@b{Submitted to the CHI '89 Conference on Computers and Human Interaction}]

@citemark (malone1, malone2, malone3, crawford, crowston, denning,
granovetter, hiltz, feld, sproull, stefik1, stefik2, rand, vonhippel,
weick, winograd )

@newpage

@subheading[Introduction]
@skip[1]

@bar[]
Missing introductory paragraph(s) and literature citations.

The paper addresses the following questions explicitly:

@begin[flushleft]
What kinds of rules do people write?
Which rules are most useful?
When do people read messages?
When do people delete messages?
Are there differences between programmers and non-programmers?
Do non-programmers write complex rules?
What kinds of individual mail strategies do people use?
@end[flushleft]
@bar[]

The Information Lens is a prototype intelligent information sharing
system developed at MIT @cite(Malone3).  Lens is designed to help users
filter and organize electronic mail.  Users can create personal sets of
IF-THEN rules, by filling in relevant fields in a message template.
Rules are organized into rulesets.  Users can specify when rules are to
run; including just prior to reading incoming mail.  Lens processes each
rule in succession, checking to see whether a message matches the "IF"
section of the rule and performs the action or actions specified in the
"THEN" section of the rule.  Common operations include: moving a message
into a mail folder, deleting a message, specifying a user-defined message
characteristic, loading specified software and printing a message.

This paper describes the preliminary results of a nine-month study of the
use of the Information Lens.  The full Information Lens system provides a
variety of features, including rules, message types and the "anyone
server".  This paper concentrates only the rules created by experienced
users of the system.  We conducted interviews and collected on-line data
to discover how people actually use Lens rules to help them with their
daily work.  We are interested in the ways in which people find the 
system useful and whether or not people freely choose to use it.
We are also interested in how effective those rules are for addressing 
the general problems of sharing information within an organization.

@b[Using Lens To Create Rules]

Users create rules with a Rule Editor, as shown in Figure One.  Note that
editing a rule is similar to editing a message.  Users fill in a message
template provided by the Rule Editor.  In this example, the user has
specified that messages addressed to the "Want-Ads" distribution list
that also contain the subject "Car" are to be moved to the "Car" folder.
Whenever a message meets these criteria, Lens will move the message 
to the "Car" folder.

@skip[1]
@center[@b{Insert Figure One about here}]
@skip[3]

@begin[quotation]
Figure One illustrates a rule that selects messages addressed to 
the "Want-Ads: distribution list about the subject "Car" and moves 
them to the "Car" folder"
@end[quotation]

All rules are associated with rule sets.  The Rule Set Editor allows
users to edit existing rules, add new rules, delete rules, change the
rule firing order, and determine the firing history of a rule.  Users can
also specify whether a set of rules should run prior to being read (by
using the newmail ruleset) or after being read (by using a folder
ruleset).

@b(A Methodological Note)

Evaluation of prototype software, while it is still in a malleable form,
is difficult.  Carefully controlled large studies, with stratified
samples of users, are premature.  On the other hand, it is highly
desirable to to learn as much as possible in the early stages of
development.  We chose to combine aspects of two approaches from other
fields of study: formative evaluation,@cite[Dick,Gagne], an empirical
approach used in the development of educational software, and rapid
prototyping, @cite[Brooks, Myers], primarily a technical approach for
the development of large software systems.  We have combined aspects of
each to meet our goals of obtaining feedback quickly and iteratively
designing the software based on this feedback.  As a result, we can
quickly evaluate improvements to the system and better understand how
users view Lens.  We can also better identify appropriate hypotheses to
test with larger populations of users.

@bar[]
Optional paragraph

First impressions are very important to the success of a project such as
this.  Version 1 of Lens had quite a few bugs and most of the users
stopped using it after a short period of time.  The initial negative
impression caused by these bugs lasted a long time and caused several
potential users to avoid the system.  The first group of users refused to
use version 2 of Lens, which was significantly enhanced and far better
supported.  Three quarters of them are now contented users of version 3.
Any attempt to have run a controlled study at the early stages of
development would have provided little insight and might have produced
some incorrect conclusions about the actual usefulness of Lens.
@bar[]


@skip[1]
@subheading(Method)
@skip[1]

The first prototype version of the Information Lens was introduced to a
small group of users in January of 1987.  The software is written in
InterLISP-D and runs on Xerox 1100 series workstations.
 Based on feedback from these users, a second version was created and
distributed to a larger group of users in September, 1987.  A third
version@foot[Version 3 was created by an early user of Lens.  He needed
to move to a new release of software for his workstation, with a new
version of mail, that did not support Lens.  He wanted to use Lens to
process his own mail, so he wrote a version of Lens that worked in the
new environment.] was developed in conjunction with a new version of the
mail system and underlying LISP environment.  Version 3 incorporated many
suggestions from version 2 and was made available in January, 1988.
Users were only able to convert to the version 3 when their workstations
were upgraded to the newer software.  Thus, start dates for use of
version 3 range over a period of several months.  Version 3 continues to
be actively used at the test site.

@b(Participants)

Members of a large research laboratory (approximately 60 people) within a
major corporation were informed about a prototype of the Information
Lens.  We asked members of the lab if they would be interested in using
Lens.  Because we were interested in active users of electronic mail, we 
solicited participation via electronic mail.

We are primarily interested in how a voluntary group of experienced
users of Lens create and use rules.  Rather than presenting all of the
data from all of the participants in all phases of the study, we have
chosen 13 users who have used  version 3 of Lens for three to seven
months.@foot[We have omitted the most experienced user of all, the author
of version 3 of Lens, because many of his rules were created to test the
system and cannot be distinguished from his regular mail processing
rules.]  Over half of these users also have extensive experience with
earlier versions of Lens.  This group includes one manager, a
manager/secretary team, 4 programmers, and 7 research scientists
(including one with formal training in computer science).  The other
researchers have formal training in physics, psychology, anthropology,
and sociology.

Those omitted from this analysis have either stopped using lens or have
not yet accumulated three months of experience with version 3 of Lens.
The primary reason cited for not continuing use of Lens was conversion to
a workstation that does not support Lens.  Several people are unwilling
to try prototype software.  Two people (one programmer and one manager)
reported that they do not find Lens sufficiently useful.

All participants in the study work in an environment that has supported
electronic mail for over a decade.  All rely on mail for both formal and
informal communication.  Their existing mail system operates in a
networked workstation environment that permits the use of separate
windows for composing, reading and browsing messages or folders. Messages
can be marked with system-defined characteristics, such as moved or
deleted, or with characteristics specified by the user.  Users can create
and name as many folders as they like.  The Lens prototype has been
designed to enhance rather than replace this mail system; participants
can use as many or as few Lens features as they like.

@b[Interviews and Data Collection]

Interviews were conducted prior to participation in the study and at 2
and 3 month intervals during the course of the study.  (Refer to Mackay
(1988) @citemark[Mackay] for a discussion of the preliminary interviews.)
The first interviews were scheduled just after the general electronic
mail announcement of the Lens study, which was based on version 2 of the
software.  Several weeks later, we demonstrated Lens at an open meeting
and invited people to try it.  Those who chose to participate in the Lens
study were interviewed again, just prior to installing Lens on their
machines.

All interviews were scheduled for one hour in the participant's office.
Each person was asked to save the current day's mail and delete
confidential messages. Participants were asked to estimate the daily
numbers of messages sent and received, the number of mail folders, the
size of the inbox and the number of distribution list subscriptions.
These answers were checked against the actual numbers for the day and
participants were asked if the day was typical.  Participants were also
asked open-ended questions about major problems and successes with
electronic mail.  They used this as an opportunity to describe their
current communication patterns, successful mail management strategies,
and problems that needed to be addressed.  They also described their use
of Lens, including a description of their rules and how they relate to
general mail handling strategies.  The actual questions are listed in the
appendix.

Version 3 of Lens was introduced four months after the initial
interviews, although only users with the updated software release could
use it at that time.  Potential users were told how to install it but
were not given any special training or inducement to try it.  Data about
each participant's use of versions 2 and 3 of Lens were collected
automatically.  Data collected included: snapshots of the current set of
rules, the current hierarchy of mail folders, a history of each user's
rule changes and the user's distribution lists.  Snapshots were taken 
every time a user modified a rule or folder.

The following data are derived from snapshots of the rules and folders of
the 13 most experienced Lens users.  We chose the first day after the
user had had three month's experience with version 3, to create a
representative, but not exhaustive, sample of rules.  Also included in
the analysis are the histories of the changes that each user has made to
rules over a period of 3 to 7 months.

@skip[1]
@subheading[Results]
@skip[1]

All participants in the study, regardless of computer experience, are
able to effectively write their own rules. (One user, with no computer
training, described his first experience with the rule editor: "It's
obvious.  You just go into the boxes and type whatever you want.").
However, users do vary in their ability and interest in writing complex
rules.  Users have the option of writing arbitrarily-complex rules in a
LISP-like language, but most choose to use the rule editor provided with
Lens.

@b[What kinds of rules do people write?]

The 13 participants in the study created a total of 180 rules, ranging
from 2 to 35 rules per person or approximately 14 each.  Most of the
rules (77%) move messages into a folder.  Some (21%) delete messages and
the rest change user-defined characteristics (1%), stop further
processing of a ruleset (1%) or print a hardcopy version of the message
(.5%).  Rules can be organized into rulesets that either run just prior
to reading new mail (newmail rules) or at the user's discretion (folder
rules).  The rules are divided approximately evenly between the two kinds
of rulesets, although individual users have strong preferences for one or
the other.  4 people, all non-programmers use newmail rules exclusively,
4 people (from each job category) use folder rules exclusively, and 5
people use both kinds of rules.

Two thirds (67%) of the rules select messages based on TO:, CC: or 
both fields together.  Previous versions of Lens did not permit the 
"TO: or CC:" construct in a single rule.  Instead, users had to write two
separate rules, one for TO: and another for CC:.  Based on numerous
requests, version 3 has a special "TO: or CC:" field, which accounts for
79% of the rules that look for an addressee.@foot[The rule editor
provides a simple direct-manipulation interface for creating rules.
While it is easy to provide users with the ability to place AND, OR or
NOT between items in fields, it is difficult to design an effective
interface that allows users to place ANDs, ORs and NOTs between the
fields. The Rule Editor has a LISP-like language that allows users to
create arbitrarily complex rules.  Some users have taken advantage of
this option, but most simply use the rule editor.] As a result of this
change, some users have reduced the total number of rules by one third
to one half.

A surprisingly high percentage (31%) of the rules select items in the
subject field.  Since the subject is less constrained than other fields,
which usually refer to known usernames and distribution lists, it is
interesting to look at the strings they select.  Approximately 30% look
for project or system names.  Another small, but important group are
those that refer to meetings or phone calls.  17% of the rules use the
FROM: field and a few (3%) @foot[These numbers do not sum to 100% because
a single rule can contain more than one field.  For example, a rule might
select messages that are both addressed to a particular distribution list
and about a particular subject.]  look for words in the body of messages.
(These were all written by one person, a very experienced programmer.)
Careful analysis of the subjects may identify standard sets of topics in
use by the organization.@foot[Version 1 of Lens actually had a topic
field for just this purpose.  However, people were confused about the
difference between subjects and topics.  This is a good example of a
technological change that also requires the support of social norms to be
successful.]  Similarly, it should be possible to identify useful message
types for the organization.  If these are used consistently, the
effectiveness of these rules will be increased.

Over half (54%) of the rules involve the processing of distribution
lists.  An even larger percentage of the delete rules (74%) involve
distribution lists and almost all of the participants (85%) use at least
one distribution list rule.  Several people commented that Lens allows
them to stay on distribution lists that they would otherwise remove
themselves from.  Lens also helps people deal with distribution lists
they are forced to join.  Users process distribution lists with both
newmail and folder rules.  Newmail rules usually move very high or very
low priority messages to a folder.  Folder rules usually sort or delete
messages that have already been read.

After distribution lists, the next most common kind of rule identifies
messages addressed to or copied to an arbitrary string (17%).  Strings
are interesting because they can identify sources of messages in
different ways.  For example, the string ".BITNET" identifies messages
from outside the company, often professional colleagues and friends.
Strings can also identify a collection of related distribution lists.
For example, the string "AI" selects messages addressed to AI, AI-digest,
and AI-interest.

The total percentage of rules for a particular type is not necessarily 
a good indicator of the importance of that kind of rule.  For example, 
each user can have an arbitrarily large number of distribution lists rules, 
but at most three rules that refer to him or herself, i.e. "TO: user", "CC:
user", and "FROM: user".  The latter make up only 11% of the total 
number of rules, yet 85% of the users had at least one and most 
people described "self" rules as being extremely useful.

Similarly, it is tempting but not accurate to believe that users with
more rules find Lens more useful.  In fact, some of the users who
reported the most satisfaction with Lens had only two to four rules.
What is important is how well the particular rules meet the needs of the
individual user.  Most users reduced their total number of rules when
they converted from version 2 to version 3 of Lens.  The addition of the
"TO: or CC:" field mentioned earlier accounts for a large part of the
reduction.  The rest is due to the creation of a smaller set of more
useful rules.  After experimenting with Lens for several months, most
users arrived at a useful subset of rules which did not change much over
time.  When these users moved to the new version of Lens, they
transferred only the rules that were useful.

@b[What Kinds Of Strategies Do People Use To Manage Their Mail?]

Rules reflect the strategies users have for managing their inboxes. Some
users like to restrict the inbox to the most important messages while
others prefer to to keep "unprocessed" messages there.  The former group
of users are more likely to use newmail rules whereas the latter are more
likely to prefer folder rules.

A special case is the use of "self" rules to move personally-addressed
messages to a priority folder.  Five people use newmail rules for this.
Each is willing to make the inbox lower priority and discipline
themselves to read priority folders first.  One person uses a self
rule in his personal folder, because he is not willing to change the 
status of his inbox.

A typical example is a senior researcher who stays off all voluntary
distribution lists and relies on colleagues to provide him with technical
information.  He uses mail to maintain an active correspondence with
colleagues around the world; these make up two thirds of his messages.
His rules correspond closely to his folders, identifying messages
addressed to him personally and messages sent via "BITNET".  He has very
few rules, but they make a major difference in his use of electronic
mail.  "When I've been gone, Lens is fantastic.  I was away for a week
and it was a pleasure to have my mail sorted correctly."

Another user converted to this strategy after using Lens for many months.
He was initially very distrustful of Lens, and first decided to use it to
help sort previously-skimmed messages in his inbox.  He refused to use
new mail rules, explaining that "Nothing happens automatically -- I look,
then sort."  This user allowed his inbox to reach an unmanagable state
with over 1100 messages.  The best he could do was collect the "old"
messages at the beginning of the inbox, move them into a dated folder,
and hope that there were no important messages within.

This person tried a new strategy, almost by accident, just before
converting to version 3.  He was preparing to go away on a trip, and
rather than converting all of his old rules, he created two new ones.
The first identifies all personally-addressed messages and places them
into a "priority" folder.  The second identifies all messages related to
a conference he was running and sent them to the conference
administrator.  When he returned, he found that this strategy was "very,
very useful" and continued using these two rules.  He has stopped trying
to keep on top of his inbox and instead, reads only the "priority" folder
on a regular basis.  He reads whatever is left in the inbox whenever he
gets a change and either files or deletes the messages manually.  He
intends to use Lens for archiving rules: "Once I get organized, it will
be extremely useful.  I hate to stop long enough to get it set up.".
After seven months, he still hasn't created folder rules.  He said these
two rules "changed my life" and no longer describes his mail as being out
of control.

This strategy does not work for everyone, especially those who find it
difficult to limit their reading of mail to reading priority folders
first.  One person described an unsuccessful use of newmail rules in
which project-related messages were automatically moved to project
folders and meeting announcements were automatically moved to a meeting
folder.  He eventually stopped using these rules because he found that he
never checked those folders.  "My inbox is the calendar I look at every
day; alot of messages I want to sit there [to remind me what to do]."  He
is also uncomfortable with using delete rules on messages are more than a
few days old.  He'd rather they remain in his inbox because "I want to
see that I forgot it."

In addition to selecting high priority messages, Lens is also used to
identify low priority messages.  Several individuals reported that they
moved messages from low priority distribution lists into folders only to
discover that they never looked at them.  People have different reactions
to this.  Some decide that this provides useful information about 
their priorities; it's a good technique for rating the usefulness 
of different distribution lists.  Other users do not mind letting the 
messages pile up and are happy to avoid the clutter in their inboxes.

Another strategy for handling low priority mail is to use newmail rules
to automatically delete them.  Since the deleted messages appear on the
screen with a line drawn through them, the user has a chance to see them
before they are expunged from the system.  ("I don't remove myself from
mailing lists, I just automatically delete the messages.  I occasionally
spot something in the deleted messages and take a look.  I'm almost
always disappointed and think that, yes, I should have deleted it.")
This person made the point that it is easier to write a rule than get on
or off of a distribution list.  He changes his rules from delete to move,
depending on his current work load and whether the topic is currently
relevant.  "It makes the cost of staying on a distribution list very
low."  One person uses a similar strategy for identifying potential rules
for handling messages in his inbox.  "If a rule doesn't fire on a set of
messages in the inbox, I let them accumulate and use [those messages] to
determine whether a special rule is needed."

Another rule considered useful by a subset of users is the "boring" rule.
An early Lens user observed that some distribution lists often carry
boring discussions about a particular subject.  Messages in a particular
discussion can be easily identified, because the subject of the message
always contains the following: RE: <subject of original message>.  Lens
version 3 allows a user to point to such an message and automatically
create a rule that deletes all subsequent related messages.  (This is an
example of "rule-creation-by-example".)  Those who uses this rule
extensively subscribe to an above-average number of distribution lists.
The 4 people use this rule are are very happy with it.  ("This boring
business is a real win!"  "This kind of thing is great!")  Another user
tried it for a while and did not find it particularly useful.  This
person, however, rarely reads distribution lists.

All of the senior members of the lab use newmail rules, although some
also use folder rules.  With one exception, all the junior members of the
lab use folder rules or a combination of newmail and folder rules.  A
larger group is required to determine whether and how this effect can be
generalized.

The different strategies for handling inboxes can be summarized as follows:
@skip[1]

@begin[enumerate]
Process mail as it arrives and leave it in the inbox until it has 
been successfully handled, regardless of priority.  (Use folder rules 
or no rules.)

Move inessential messages out of the inbox and use it as a 
repository for things to do and unprocessed mail.  (Use folder, 
possibly newmail rules.)

Move all important messages into separate high-priority folders 
and use the inbox as a temporary storage place for lower-priority 
items.  (Use newmail rules.)
@end[enumerate]

The two managers who use Lens both share mail-processing strategies with
their secretaries.  All of them would like to improve mail handling
efficiency.  In one case, the manager wrote the rules himself and in the
other, the secretary wrote the rules.  He uses newmail rules exclusively;
she began with newmail rules and switched to folder rules exclusively.
The manager is careful to limit his reading of mail to 30 minutes a day.
She likes to preview all of the messages, after which she finds it
"easier to find mail that's been sorted with Lens rules".  He keeps only
priority mail in his inbox folder and uses Lens to forward messages to
his secretary.  He is somewhat disappointed in Lens, because it "didn't
save me enough time".  On the other hand, he is one of the most long term
users of Lens.  The secretary is pleased with Lens, although she
continues to find mail "completely overwhelming" and says says that most
of her job stress comes from mail.  Interestingly, she has some of the
most complex rules of any of the users.

The relationship between rules and folders is interesting.  4 people,
representing each job category, have almost or exactly a one-to-one
correspondence between rules and folders.  Others have significantly more
folders than rules, but each rule relates to a particular folder.  The
rest maintain only a small overlap between folders and rules.

@begin[comment]

@begin[format]
Managers:	10-8/12    4-4/38
Researchers:	8-5/58     7-7/15    4-3/6      5-3/51 2-2/55 5-5/35  16-15/17
Programmers:	30-30/38   18-16/67  16-16/85   8-8/37
@end[format]

@end[comment]

@b[How Do Rules Change Over Time?]

Although most people arrive at a relatively stable set of rules after a
period of a month or two, some continue to fine-tune their rules to
handle the current set of projects, distribution lists, and topics of
interest.  Users with a small number of "self" rules have little
incentive to change their rules whereas those who use Lens to organize
large quantities of information have an on-going need to update the
details of their rules.  The average number of rule changes per month is
6.5.  Most people modified their rules between 4.5 and 7.9 times per
month and two people averaged over 10 changes per month.  The single most
commmon rule change is to the "boring" rule, presumably because it is so
easy to create and people are also more likely to remove strings that are
no longer relevant.  The top four "rule-changers" used boring rules.
(Only one of these four was a programmer.  The others were researchers.)

@b[What Kinds of Delete Rules Do People Use?]

One of the most commonly asked questions about Lens is what rules do
people use to delete messages.@foot(There is often an unspoken fear that
accompanies this question, based on the suspicion that Lens users will
delete the questioner's mail messages.  This is actually the opposite of
what happens.  Lens users are more likely to see personally-addressed
messages than those without Lens.)  Approximately one fifth (21%) of the
total number of rules delete messages.  The most common use is to delete
messages from low-priority distribution lists (74%).  Only 5 rules (13%) 
delete messages that refer to a person's name.  In each of these cases, 
the rules use multiple fields to further qualify the type of message.

In one case, a part-time employee sends out messages to the entire lab 
announcing new fitness classes.  In another, an outsider sends messages 
about his personal seminars to the company distribution list.  In both 
cases, the senders of the messages are misusing the system, but appear 
to be outside of the usual social pressures that would normally prevent
this kind of behavior.  Even though it is unlikely that the Lens user 
will want any particular messages from either sender, the rules are 
still qualified to filter out only messages about the unwanted subject.
Personal messages from either person would get through.

Table One shows the kinds of rules that people wrote to delete messages.
The top section shows the breakdown by fields; the bottom section shows 
the breakdown by types of items within fields.  The total percentages 
in each case exceed 100% because delete rules can have more than one 
field or item per rule.

@b[@center{Table One}]

@bar[]
@begin[format]
@tabclear[]
@tabset[1in, 3in, 3.5in]

Total delete rules with the following fields:

@\TO:		@\26	@\68%
@\CC:		@\16	@\42%
@\FROM:		@\ 9	@\24%
@\SUBJECT:	@\13	@\34%
@\TEXT/BODY:	@\ 5	@\13%

@\		@\n=38	@\total > 100%

Total delete rules that refer to:

@\self: 		@\ 2	@\ 5% 
@\person: 		@\ 5	@\13%
@\string:		@\19	@\50%
@\distribution list:	@\28	@\74%

@\		@\n=38	@\total > 100% 
@end[format]
@bar[]

Deletion rules are more complex than rules that move messages to folders.
Complexity can be measured in different ways.  We have chosen to define
complex rules as those with more than one field (except those with "TO:
or CC:") or with multiple items in a field.  By this definition, 36% of
rules are complex, and users are six times as likely to use "OR" as "AND"
between items in fields.  Experienced programmers are no more likely to
use complex rules (33%), than non-programmers (39%), although the 2
people who do not use complex rules are both non-programmers.  60% of
delete rules use more than one field (not including the "TO: or CC:"
construct), whereas only 32% of move rules use more than one field.
Rules that use "AND" between fields in the message are more restrictive
than those that use "OR" between fields.  (The latter are equivalent to
creating several simple rules, one for each field.)  Users create more
restricted complex rules (those with "AND" between fields) when deleting
messages (32%) than when moving messages (17%).  

One explanation for this is that deletion is more "dangerous" than moving
because an error has greater consequences, i.e. the accidental deletion
of a message.  Similarly, newmail rules are somewhat more dangerous than
folder rules, because the former may result in an important message being
missed.  It is not surprising that newmail rules are more qualified than
folder rules.  Almost all of the complex rules in newmail rulesets
contain "AND" (26/28 or 93%), whereas fewer than half of the folder
rulesets contain "AND" (13/34 or 38%).  On the other hand, it is not
really true that newmail rules are more cautious than folder rules.  In
fact, newmail rules are more likely to delete messages (29%) than folder
rules (14%).

@skip[1]
@subheading[Discussion]
@skip[1]

This needs more work...!

The use of rules provides useful insights into the ways in which people
use their mail.  If it is true that mail reflects the work activities of
individuals and groups within organizations, then these rules mirror
cooperative work styles in the organization.  

Patterns of mail use are very individual.  Even (or especially)
experienced mail users are often surprised at how others use mail.
We also found that some people were not particularly good at 
predicting how they would use rules for managing their mail.

(Writing about Email is a bit like writing about education -- everybody
is an expert.  Most readers use mail extensively and feel that they "know
what it's like".  But the data show that there's quite a range of
patterns in use of Email and thus Lens.  Also, it shows that people's
predictions of their own uses of Lens may not be accurate.

The preliminary interviews identified distinct preferences for when rules
should be run.  Individuals who feel the need to be more efficient with
their time are primarily interested in rules that run @i[before] they
read the messages.  This way, they can sequence the processing of
messages from most to least important.  Lens thus helps them
@i[prioritize] their handling of electronic mail.  Others want to
continue reading all of their new messages, but would like to gain better
access to messages that have already been skimmed and partially
processed.  These people want rules that run @i[after] they read
messages.  Lens helps them clean up out-of-date folders and
systematically @i[archive] messages for subsequent retrieval.

As mentioned earlier, not all users accurately predicted their eventual
use of rules.  In particular, one staunch "archiver" ended up using
newmail rules exclusively.  

The issue is not which ruleset people use, but how the perception of 
a message changes over time and what different strategies people 
use for dealing with those changes.  It is naive to think that 
rules that simply identify the content of messages will be sufficient.  

We did not find major differences among job categories, except 
that programmers use a larger number of rules.  Seniority was 
a more important discriminator.  Senior members of the laboratory 
are more likely to use that help prioritize processing of mail, 
all use newmail rules, and are not afraid of missing information.
Junior members, with a few exceptions, are more interested in 
rules that help organize their mail and all but one use folder rules.
It will be interesting to see if these are differences in the 
kinds of jobs that these two groups of people perform or 
whether they are related to ...

@skip[1]
@subheading[Acknowledgements]
@skip[1]

We would like to thank Maya Bernstein for her cheerful and extensive
tabulation of the data.  We would also like to thank the participants in
the study for their thoughtful comments and willingness to discuss their
different strategies for managing electronic mail. 

@skip[1]
@subheading[References]
@skip[1]

@skip[1]
@bibliography

@newpage
@begin(subheading)
Appendix A:  Data Collection
@end(subheading)

@b[Interview Questions:]

A.  @ Mail Use Questions:
@skip[1]

@begin{enumerate,justification off}
How many messages did you send today?

How many messages did you receive today?

Is this a typical day?

How many mail folders do you have?

How many messages are in your inbox?  

Is this typical?

How many distribution lists do you subscribe to?  

How often do you read your mail?

Do you read all of your mail?

What percentage of messages do you wish you had never seen?
@end(enumerate)

B.  @ Open-ended questions: 
@skip[1]

@begin{enumerate,justification off}
Describe how you use mail.

In what categories do you place your mail messages?  

Can you think of times in the past week in which you needed 
technical information?  What did you do?

Can you think of times in the past month when you've looked 
at a previously filed message?  Describe the procedure you 
used to find it.

What kinds of rules would you like to process your mail?
@end(enumerate)

@b[Automatic Data Collection:]

A.  Rules

@begin[enumerate]
Ruleset names and contents

Text of rules

Changes made to rules 
@end[enumerate]

B.  Folder Hierarchy

@begin[enumerate]
Folder names

Number of messages automatically moved into each folder
@end[enumerate]

C.  Distribution Lists

@newpage

@subheading[What needs to be done:]
@skip[1]

@begin[enumerate]
Come up with a snappy introductory paragraph.

Add references to the introduction and conclusion.

Revise the conclusion.

Acknowledgements OK?

Shorten it if possible.
@end[enumerate]

@skip[1]

@begin[enumerate]
Permission from Xerox

Paper and data to Stu

Permissions from co-authors
@end[enumerate]


Titles:

@begin[itemize]
Reflections On The Use Of The Information Lens

Reflections on Communication:  An Empirical Study of the Information Lens
@end[itemize]

@newpage

@begin[comment]
@b[JUNK]


complex:		17/38	45%	(not  "to or cc")
   (complex and:	12/17	71%  
   (complex or:)	 5/17	29%	

to or cc:		 6/38	16%
simple:			15/38	39%	(just one field)


population complex:	63/180  35%	(not  "to or cc")
   (complex and:)	38/63	60%  
   (complex or:)	25/63	40%	


12 delete folder rules
75 move folder rules
87 folder rules

26 delete newmail rules
64 move newmail rules
90 newmail rules

38 delete rules
139 move rules


(2 stop rules and 1 hardcopy rule = total of 180 rules.  3 setcharacteristic
rules in conjunction with other rules -- multiple rule actions.)

(Of the delete rules, 4 people use exclusively newmail rules, 2 use
exclusively folder rules, and 2 use both folder and newmail rules.)  Of
the 38 delete rules, 14 (37%) are folder rules and 24 (63%) are newmail
rules.


@b[Automatic Writing of Rules:]   Analysis of the rules may identify 
what rules may be most useful to people.  We can try to determine 
if there is some set of "default" rules that everyone should have.
Note that people really do have different ways of processing the 
mail in their inboxes, managing their folders, etc. and view their 
problems with mail very differently.  So it is unlikely that there 
will be a universal set of rules.

@b[Implicit message types]

@b[Multiple rulesets]  The finding that people want control over 
when their rulesets fire supports the idea of generalized user 
agents.  Also, need "meta agents" that watch the patterns of 
firing rules.

Some people want an "exciting" rule, similar to the boring rule, that
allows them to create rules that look for interesting messages "like this
one".  (This is a request for the anyone server.)


"I'll make more complex actions when I establish my archiving ruleset."

Version 3 of Lens also allows users to create rules that call other sets
of rules.  For example, one set of rules can identify and mark
characteristics, i.e. importance, and subsequent rulesets can process the
messages according to the user-defined characteristics.  One person uses
this to specify user-defined characteristics while moving messages.
Users can also specify more than one action per rule.  This was used
twice to specify a user-defined characteristics while moving a message to
a folder.


This may be because the purpose of the deletions is
different in the two cases.  With newmail rules, the purpose of a delete
is to prevent the user from seeing the message at all.  (and of course
there are big differences among users as to whether they want this to
happen.  Usually, only people who want to get off a distribution list
anyway delete these messages.  ("It's easier to change a rule than change
a mailing list.")   With the folder rules, messages have already 
been seen by the user.  This is a way of cleaning them up.
Some people move a group of low-priority messages into a folder 
and then look at them occasionally.  At those times, they usually 
delete everything in the folder.  Thus, they don't need a folder 
rule to do it.



Are some people more likely to use delete rules than others?  Yes.
It appears that programmers are more likely to use delete rules.

@begin[format]
Managers:	 0/5    2/14
Researchers:	 6/14   0/7    0/4     1/6    0/2   3/8   1/18
Programmers:	 2/33   10/18  13/35   0/16

Managers:     2/19 =   10.5%
Researchers:  11/59 =  18.6%
Programmers:  25/102 = 24.5%

Total:        38/189 = 21.1%
@end[format]

The numbers of rules created by individuals in each job category are
summarized below.  Not surprisingly, programmers write the largest number
of rules.  

@begin[format]
@tabclear[]
@tabset[1in, +.7, +.7, +.7, +.7, +.7, +.7, +.7, +.7, +.10]

Job Category:	@\  @\   @\   @\   @\   @\   @\   @\mean  @\range

Managers:	@\5   @\14  @\    @\   @\   @\   @\    @\9.5   @\5-14
Researchers:	@\14  @\7   @\4   @\6  @\2  @\8  @\18  @\8.4   @\2-18
Programmers:	@\33  @\18  @\35  @\16 @\   @\   @\    @\13.8  @\16-33
@end[format]

An interesting difference between people with computer science
backgrounds and non-programmers is the use of "NOT".  Several of the
latter "discovered" the power of not and were very excited about the
possibilities.  For example, moving all messages that are NOT
addressed to you to a less critical folder is a way to keep the 
inbox clear for new and important items.  This rule gives people 
who want to use the inbox as a "to do" list an easy way to 
remove unimportant messages from the inbox and does not force them 
to read a separate "priority" folder.

Finholt:  and a string of Not a person and to or cc himself.

Brown:  if cc decato or brown and to or cc library move to library requests.


"Used to archive messages and will do it again.  Just haven't gotten 
to it yet."


=====================
We can also look at "self" rules by job category:

@begin[format]
Managers:	 1/5    3/14
Researchers:	 3/14   1/7    3/4    0/6    1/2    0/8   1/18
Programmers:	 3/33   1/18   2/35   1/16
@end[format]

The only two individuals without self rules are researchers.

=====================


There are many kinds of DL's.  Small groups that have their own 
dls treat them almost the same as personally addressed messages.
Everyone on the list is actively involved and messages are usually 
directly relevant to the individual.  Organizational announcements 
are different from completely voluntary dls such as "sports" or 
"jokes".  Interest-based dls and project-based dls are different 
still.  

@end[comment]

