Choice from a Large Set
Examples:
-
Scrolled list box
-
Combo box (drop-down list)
-
50-piece socket wrench set
-
Book index
Context: The artifact shows, or allows the user to
set, a value which is one out of a large set of possible values (more than
10). This often happens on Forms and Control
Panels, and sometimes on Status Displays;
it is very similar to Choice from
a Small Set., and shares much of its context with Sliding
Scale.
Problem: How should the artifact indicate what kind
of information should be supplied?
Forces:
-
The user should see all the possible values, to put the actual value in
context.
-
If the user needs to set the value (not just look at it), they should know
what choices are available.
-
The user should be able to find the value they want quickly.
-
Large numbers of things take a long time to read and take up lots of space.
Solution: Clearly show the selected value up front;
organize the set of possible values, but hide them nearby if they take
up too much space. Put them on a separate working surface, for
instance, or in a scrolled area or combo box in a GUI environment, where
they are only a single gesture away. Organize them in the way most appropriate
to how the user will be searching -- alphabetically if looking for names,
numerically for a font size, most-often or most-recently used for a document
to edit, etc. Allow a user who knows exactly what they want to directly
enter the choice, as by typing, rather than by laboriously searching it
out.
Resulting Context: Good
Defaults may let the user look at the default value, judge it to be
OK, and move on without even bothering to set the value. If the choices
are pictorial, or are cryptic in some other way, Short
Description may be needed to describe the choices further.
Notes: Scrolled combo boxes are really only necessary
if the dropdown list is going to run off the edge of the screen -- it's
easy to miss the choices beyond the visible area, and it's awkward for
many people to drop down the list, then move to the scroll bar (or buttons),
then scroll up, then down, etc. It takes the bad features of scrolled lists
and makes them worse, first by making you show the list and then by shrinking
the scrollbar.
Comments to: jtidwell@alum.mit.edu
Last modified May 17, 1999
Copyright (c) 1999 by Jenifer Tidwell. All rights reserved.