The magical number seven, plus or minus two

November 27, 2007 at 7:27 am 2 comments

In an earlier post on best practices for likert scale questions, I made reference to an article “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information”. A reader pointed out to me that this is one the most famous social psychology articles (by George A. Miller, 1956).

A main conclusion of the article is that most people can only deal with seven ideas at a time. Very clever people can manage up to nine and less skilled people may only be able to concentrate on five ideas at once.

Putting this theory into practice, I can see plenty of examples which call out for the “seven point limit”, such as:

  • Number of chapters in a report
  • Number of recommendations in reports (if there are more than seven then they should be broken down under sub-headings)
  • Number of points on a likert scale question (see my previous post on this)
  • Lists of variables/aspects that must be ranked/rated on surveys (e.g. “please rate the following aspects of the website..”)
  • Items on a checklist to be assessed (see my previous post on checklists)

And that’s only five ideas so us less skilled people can cope…


Entry filed under: Evaluation reporting, Evaluation tools (surveys, interviews..).

Likert scale & surveys – best practices The ultimate user test?

2 Comments Add your own

  • 1. jen_chan, writer  |  November 30, 2007 at 2:22 pm


    Well now… this is a particularly interesting piece of information. And it’s quite useful too, especially when one is in the business of advertising and marketing. And when one intends to spread information, using this seven-point system should be able to help the whole campaign be even more effective to the target audience.

  • 2. Glenn  |  December 2, 2007 at 3:29 pm

    Hi Jen,

    For sure a seven-point system is also useful in campaigning in terms of number of points that can reasonably be recalled by an audience – that’s how I woud interpret it for advertising and marketing.


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