Interface Design for SunSITE statistics
http://sunsite.unc.edu/stats
User Analysis Documentation:
Accessing Statistics on SunSITE
Those that maintain archives on SunSITE do so with full
control of their archives. SunSITE is a digital library and makes no claims
of authenticity for content and does not seek to exert editorial control.
In contrast, the goal is to facilitate the accessibility of information.
The management of SunSITE does not purposefully set out to monitor content
or the activities of collection owners. As a result, and for reasons of
liability, SunSITE knows little about those persons and organizations that
maintain archives on SunSITE.
The user group for this interface will vary greatly in
computational knowledge. This creates an interesting challenge for design.
Some of the users will seek very specific information from the Web page
while others will come with little knowledge of the system and little idea
of what information is available.
The users maintaining collections on SunSITE are the primary
users for this system. These archive owners on SunSITE tend to be experienced
users that seek a quick display of statistical information that they can
display for sponsors.
The less experienced users will be visitors to SunSITE
or less computer literate users that maintain archives in SunSITE. Because
SunSITE encourages diverse collections, some of the managers of archives
are not necessarily expert users. The challenge lies in trying to create
an interface that allows experienced users to quickly extract the specific
information they seek while offering cues for the infrequent user.
Psychological characteristics
-
Cognitive style: The diverse array of users cannot
be specifically categorized for cognitive styles. Most of the users will
be familiar with the basics of Web interfaces. The interface will therefore
conform to current Web user expectations.
-
Attitudes: The users will be coming to the page by
choice and will have a very positive attitude toward computing. Some will
come with expectations and others will come with simple curiosity. User
expectation will be for information about the number of times the pages
have been accessed. This information will be provided along with options
for table layout or graphs. Some users may seek information about where
the pages were viewed from, but this is beyond the scope of the program.
The logs used to generate the stats do not include this information.
-
Motivation to use the system: For some the motivation
will be work related but, for most it should be curiosity. We are a non-profit
archive; most users do not have sponsors to satisfy.
Knowledge and experience:
-
Level of education: (Novice to Expert) Users should
have a relatively high level of familiarity with the system. The access
to the interface will be through a Web browser and users will need to be
able to use a browser to get to it. Those that will be most interested
in the statistics will be users with archives on SunSITE and will therefore
be familiar with the Web. The people with archives on SunSITE tend to have
at least some college, expert computer skills, and moderate ability to
communicate in English.
Physical characteristics:
Users perceptual abilities and motor skills may vary, but
if they are common web users they will have the tools to use the interface.
Users will posses the skills necessary for browsing, mouse movement and
clicking, and World Wide Web navigation.
Web Statistics Interface for SunSITE
The prototype that has been created is for a World Wide Web
page. The page is the interface for requesting statistical information
about archives on SunSITE. The system allows users to specify the directories
that they want information about. It also allows for output as either a
table or bar graph.
The goal of the interface is to create a fast and easy
to use system for finding out how many hits specific directories have experienced.
The system includes a very brief form to pass the necessary variables to
the CGI (common gateway interface) script that carries out the operations.
The form includes a text field, radio buttons, and pull down menus. All
of these form elements are part of the HTML 3 specification.
The Uniform Resource Locator (URL) for the stats page
has been sent to those that maintain archives on SunSITE through an email
list. This is currently the only way that the Web page has been publicized.
Owners of the archives will be notified of any updates via the list. While
the page in intended primarily for these users, a link to the page may
be added to a high level page so the general public can check the number
of hits in the future.
Rationale for Design Decisions
Statistical Information Interface on SunSITE
The Overall Design:
There are a number of points that were important in the overall
design of the Web page. The first of these was the file size of the HTML
document. When considering design issues it is important to consider the
medium that the system is operating on. While the user will be using a
computer, the actual document must travel over the Internet. This can lead
to latency problems that will increase as the file size increases. To avoid
these problems the page was kept simple and small in size.
From a creative perspective, there was a desire to incorporate
exciting graphics and more interactive functionality with simple programs
supported by popular Web browsers. These designs would not make the interface
any more efficient and would make the file larger. In an a study of the
Web and user interaction, Nancy Lightner, Indrail Bose, and Gavriel Salvendy
(1996 *998), found that users' two main concerns were speed of access and
searching for specific information. The current system is designed to facilitate
these needs as efficiently as possible.
The Web page has been made as compact as possible while
maintaining logical groupings for the tasks. One of the key reasons for
keeping the actual size of the page to a minimum is to ensure that the
whole system is visible upon download. A major problem for Web designers
is the lack of consistency and control over user systems. Varying monitor
sizes, processor speeds, bandwidth limitations, and browsers will affect
the layout and function of a design. The design for the stats page should
enable the whole page to be visible on just about any system without any
scrolling necessary. In this way the user can see all the variables available
for input. This should eliminate confusion over how much information is
needed and how to submit the information.
The overall design includes a form, menus, and buttons
as described by Deborah Hix and H. Rex Hartson in Developing User Interfaces
Ensuring Usability Through Product and Process (1993 *pg72). The interface
includes a number of the guidelines as specified in their book. Some of
the key guidelines used included consistency and visually appealing layout.
User tasks are set together in logical groupings with visual cues delineating
the different areas. Another guideline that is followed is the use of visual
cues in various fields. This is an important feature to help users understand
what is expected for each task. Two similar guidelines that are also reflected
in the design are the use of default values in fields and explanatory messages
for expected field inputs. With the implementation of these cues the system
should seem logical to the user and help to avoid confusion.
Below is an explanation of design decisions for each of
the tasks for the system.
Enter the URL:
A text field or form fill-in is used to enter the address
of the archive to query. Since the statistics are being made available
primarily for the use of the collection managers users will know the desired
URL. There is also a sample entry under the text field to illustrate the
proper format. Research has suggested that this type of form fill-in requires
little training and simplifies data entry ( Palanivel and Helander *pg
141). In addition, due to the enormity of the collections available it
will not be reasonable to offer a menu of choices for all directories.
An important feature of the text field is the visual cue
offered. The field already contains the first portion of a SunSITE URL.
This serves two functions; it cues the user about the expected input format,
and it saves the user from having to enter this portion of URL. The aim
is to make this task as quick and clear as possible.
Start and End Dates:
These values will be presented to the user using pull-down
menus. The range of dates to be queried will be determined by chosen values
from a start date menu that will allow the user to choose a month, day,
and year. These values will be compared to an end date menu with similar
menu choices. The choices for the month will be English abbreviations,
the days will range from 1 to 31, and the years will be given from 1996
to the present. The numbers and months are organized in a reasonable fashion
to help improve performance ( Palanivel and Helander *pg 137). The available
logs only go back to 1996, hence the date limitation.
The menu design was chosen to indicate to the user what
values are available and to help eliminate confusion. The format that the
statistics code needs to process could be confusing if entered in a text
field. The different formats for representing dates in different cultures
could also lead to many errors. Menus offer a number of advantages over
other designs. They can reduce errors, eliminate the need for memorization,
and require little training (Hix and Hartson *pg 62).
There is a lot of information available on the use of
menus in interface design. Carey, Mizzi and Lindstrom (1996) did an investigation
into user response to pull-down menus and traditional menus. In their work
they found that users preferred traditional menus. Despite this, the stats
page includes pull-down menus. There are two reasons for this design. The
first reason is the focus on compact design and screen real estate. Traditional
menus require more screen space (preece, *pg265). The second reason is
that most users will be expert users and the study found that they less
resistant to pull-down menus. It seems that expert users are more familiar
with the pull-down design.
Display By:
The system can currently allow the user to choose whether
they want daily or monthly statistics. These choices will be presented
to the user with radio buttons. Radio buttons have been chosen so the user
has cues as to what variables are available. In addition, radio buttons
are exhaustive and mutually exclusive (Hix and Harton, *pg 64). This makes
clear that the user is to choose only one value and it shows which is currently
selected. Another advantage is that it allows for a default selection at
startup.
Output Format:
The output format choice will be made using radio buttons.
The reasons for this design are: The choice of radio buttons allows the
user to see what values are available; A default can be set; and users
can see current choice. If there were many formats to choose from radio
buttons would not be practical.
Recursion Level:
The recursion level, or depth to be descended into the directory,
will also be chosen with radio buttons. The system currently only supports
viewing one directory deep because of concerns over processor limitations
on SunSITE The term "recursion level" has been defined on the page to help
users understand the task.
Submit/Reset:
The submit/reset task is presented using push buttons (Hix
and Hartson, *pg 62-63). The buttons are clearly marked and the function
of each is clear. In addtion, push buttons are common to forms on Web pages
and should be familiar to the intended users.
Further Consideration:
The original plans for output choices (line or bar graphs)
will not be incorporated in the early prototypes. The focus will be on
creating an easy to understand query interface that will deliver the desired
results to the user.
Another consideration is a very fast access design for
the expert user. The system will include a separate web access point that
will not offer cues or options but will be accessible by simply entering
the a specific URL that includes the directory for which the statistics
are desired. The instructions for the expert system will be available from
the main interface page. In this way the frequent user can learn the faster
system if desired. The URL for the main statistics page will be made available
through the channels of communication available at SunSITE. The primary
channel will be the webgroup list, a collection of email addresses for
all collection managers on SunSITE.
Usability Specifications:
(Based on Hix and Hartson, 1993, pg 223)
| Usability Attribute |
Measuring Instrument |
Value to be Measured |
Worst Acceptable Level |
Current Level |
Planned
Target Level |
| Initial performance |
"Enter directory in text field"
tasks per benchmark 1 |
Number of errors on first trial |
0 |
0 |
0 |
| Learnability |
"Get single recursion table of stats for specific day"
tasks per benchmark 6 |
Number of errors on first trial |
2 |
0 |
0 |
| Initial performance |
"Get single recursion table of stats for specific day"
tasks per benchmark 6 |
Length of time to successfully get stats on first try |
90 seconds |
45 seconds |
30 seconds |
Scenarios
These scenarios are based on the scenarios for design in "Will
the Real Scenario please Stand up?," by Robert Cambell
The frequent user of the statistics
David is the creator of the Neurosurgery pages in the SunSITE
archives. David spends a great deal of time and effort updating the information
on the pages. His hope is that these pages will be a resource used by neurosurgeons
around the world. Now David wants to dedicate more of his time and funding
to this project.
In order to get the permission from his superiors, David
must prove that the pages are being utilized by a wide audience. The supervisors
ask that David get statistics each week and make the information available
for them. They state that they don't want anything fancy, just the numbers.
David goes to http://sunsite.unc.edu/stats where he can get the statistics
he needs.
David enters the directory for his research, dates for
the last 6 months, the monthly output, and chooses a table format. The
data comes back with number of hits for each page within his directory.
He prints out this information and has it sent to his supervisor. The word
comes down that these statistics are too difficult to interpret. Now David
must find a way to display the information in a more usable format. David
goes back to the stats page, but this time he sets the output format for
bar graphs.
The infrequent user of the statistics
Carl has just recently been given an account on SunSITE and
has created a resource for educators in correctional institutions. . He
has no funding for his work and does it on his free time. He got a message
about the new statistics page that is now available on SunSITE. Out of
curiosity he checks it out. When he gets to the page he sees the first
instructions to enter the directory that he would to get statistics from.
He does this and then moves down the page making choices for the presentation
of the material. He chooses the statistics for the last week and has them
displayed as bar graphs.
General description of task characteristics
How frequently do users perform the task?
The users' frequency of use will vary greatly with each
user. Those that are getting funding to maintain archives will have a greater
incentive to check statistics than those that have creative collections
they maintain in their spare time.
What are the time constraints on the task?
The task will take very little time to use when the system
is running properly. It will allow those that have frequent use to get
very quick results while providing cues for the infrequent user.
Is system use mandatory or discretionary?
The use of the system is discretionary.
Questions related to the environment or context
How important is the task?
For many the task will be one of satisfying curiosity.
In contrast, some users will depend on the statistics as an indication
of how useful their archives are and if it is a good investment of time
and energy.
Where is the task performed?
The task can be performed from anywhere with an Internet
connection and a web browser. Most users will use the system from where
they normally work with the Web. For most archive owners that will be here
in the United States, but for some collection owners it will be from other
continents.
What is the relationship between the users and the data?
In some cases the data will reflect the number of http requests
for their pages or in other cases the information will show activity on
a page that the user doesn't have a part in creating.
What other tools does the user have?
Expert users can try to put into place alternative statistical
gathering agents but this is difficult and not recommended. These agents
require extra processor power that can degrade SunSITE performance if there
are many such programs running.
What is the turnover rate among users?
After the initial implementation the user turnover rate will
be low. The exception is the curious visitor to sunSITE that decides to
check the stats.
Questions related to the complexity/difficulty of the task
How complex is the task? How difficult is the task?
The task is very simple for those familiar with the World
Wide Web. All the parts of the interface are common to Web pages.
How structured is the task?
The task is well designed and structured for ease of use.
The interface is designed to reduce errors while offering as many options
as the current software can support.
What training will be provided? How is the task learned?
There will be no training besides the information made available
on the system. There are a number of cues and examples to support users.
What happens when things go wrong?
When things go wrong the user will get information other
than he/she was looking for. The name of the directory that is being queried
appears at the left of the table. The names of lower level directories
and files also appear in a cell at the left. If an invalid directory is
entered a table will display with the name of the incorrect data at the
left and all other variable showing zero. The user can simply go back to
the page and re-enter the data.
GOMS Task Description
Goals:
Tasks:
Actions:
Hierarchical task analysis
GOMS Task Description
Method for accomplishing goal of obtaining Web page access statistics on
SunSITE.
Step 1 Start browser.
Step 2 Accomplish goal of getting to the GUI stats page.
Step 3 Enter top level directory to be queried in text
field.
Step 4 Choose start date from pull down menu.
Step 5 Choose end date from pull down menu.
Step 6 Choose display format from radio buttons.
Step 7 Choose output format from radio buttons.
Step 8 Choose recursion level from radio buttons.
Step 9 Submit query.
Step 10 Return with goal accomplished.
Bibliography
Hix and Hartson, pg 223 for the interaction chart.
Preece for Hierarchal task analysis chart, pg 415
Preece for GOMS pg 420.
Robert Cambell Wll the Real Scenario please Stand
up
NJ Lightner Problems it te WWW
JM CArey
Robert Cambell, Will the real scenarios please stand up.