Card sorting

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Drawing of a person sorting cards

Card Sorting is a technique for exploring how people group items, so that you can develop
structures that maximize the probability of users being able to find items.
Card Sorting:

  • Is easy and cheap to conduct
  • Enables you to understand how ‘real people’ are likely to group items
  • Identifies items that are likely to be difficult to categorize and find
  • Identifies terminology that is likely to be misunderstood.

When is Card Sorting appropriate?

Card Sorting is appropriate when you have identified items that you need to categorize.
Card Sorting is particularly useful for defining web site structures.

How is Card Sorting conducted?

Card Sorting can be conducted in a variety of circumstances using various means – one-on-one,
during workshops, by mail, or electronically. The following is the basic process.
Names of items to be categorized are printed on individual cards. Cards should be large
enough to accommodate the names in a font that participants can read easily when spread out
on a desk or table-at least 14 point.

Participants are asked to group items in a way that makes sense to them.

Participants may also be asked to name the resulting groups.

Once all participants have completed the exercise, enter the data in a spreadsheet, and
examine the groupings. There will be general agreement about many items, and these groupings
will be fairly apparent. For example, all participants may group ‘Technical Support’ with
‘Complaints’ and ‘Product Assistance’.

You can use cluster analysis to get a pictorial representation of the resultant groupings.

Pay special attention to items about which a consensus does not exist. Would re-naming the
item improve the situation, or does it need to be included in more than one category?

Who should participate?

Make sure that all participants are representative of the eventual users of the structure you
are designing.
Try to get as many participants as convenient, and at least six. However, be aware that the
more participants you have, the more data you will need to analyze.
People vary widely in the amount of time they take to sort cards. As a rule of thumb, allow
half-an-hour for a participant to sort 50 items.

Variations

There are many variations on the basic technique.

By making the cards slightly larger, you can add some simple questions. For example, ask
whether terms are understood (yes/no/unsure) and whether there are suggestions for
alternative terms.

It is possible to have people collaborate in grouping the items. However, this runs the
risk of reaching a consensus that is not an accurate reflection of any one individual’s
perceptions.

Preparing for a Card Sort

  • Ensure that each term is as clear and unambiguous as possible
  • Ensure that you have included all the items you need to categorize
  • Shuffle or randomize cards prior to each participant session
  • Script a set of instructions so that all participants have the same understanding of the process
  • Leave participants alone while they are sorting the cards to avoid placing them under unnecessary time pressure, but make sure they can contact you easily to ask questions or when they have finished
  • Provide additional blank cards for people to write group names
  • Provide rubber bands so that people can gather groups of cards together.

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