[development] APC and Web Networks Release Drupal Usability Report

[inkfree press]

"Neil Drumm" wrote:

> 
> From the report: "Binary options should use two radio buttons, one for each of
> the states."
> 
> From Nielson's Alertbox: "A stand-alone checkbox is used for a single option
> that the user can turn on or off"
> (http://www.useit.com/alertbox/20040927.html).


These are distinct interface (and logical, more precisely) elements.

The first you reference is a 'binary' object group. That is, it is an object
that has only 2 states (represented by the buttons in the group), but one of
the states is required.

The second logical element, the checkbox, is a 2-state object which may be
value-less.

Often, but not always, 'valueless' is logically equivalent to some other
value (say, zero).

Therefore, the UI principle to consider to distinguish the two interface
elements is:

    radio button -- when a value is required to be provided

    checkbox -- when a value is able to be toggled (to the 'no value' state)


Again, often but not always logically equivalent.

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