jsPsych/docs/plugins/jspsych-maxdiff.md

jspsych-maxdfff plugin

The maxdiff plugin displays a table with rows of alternatives to be endorsed as 'most' or 'least' on a particular criteria (e.g. importance, preference, similarity). The subject responds by selecting one radio button corresponding to an alternative in both the 'most' and 'least' column. The same alternative cannot be endorsed as both 'most' and 'least' simultaneously.

Parameters

Parameters with a default value of undefined must be specified. Other parameters can be left unspecified if the default value is acceptable.

Parameter	Type	Default Value	Description
alternatives	array	undefined	An array of alternatives of string type to fill the rows of the maxdiff table.
labels	array	undefined	An array with exactly two labels of string type to display as column headings for the criteria of interest. Must be in the order of 'most' (first), then 'least' (second).
randomize_alternative_order	boolean	false	If true, the display order of alternatives is randomly determined at the start of the trial.
preamble	string	empty string	HTML formatted string to display at the top of the page above the maxdiff table.
required	boolean	false	If true, prevents the user from submitting the response and proceeding until a radio button in both the 'most' and 'least' columns has been selected.
button_label	string	'Continue'	Label of the button.

Data Generated

In addition to the default data collected by all plugins, this plugin collects the following data for each trial.

Name	Type	Value
rt	numeric	The response time in milliseconds for the subject to make a response. The time is measured from when the maxdiff table first appears on the screen until the subject's response.
most	string	The alternative endorsed as 'most' on the criteria of interest.
least	string	The alternative endorsed as 'least' on the criteria of interest.

Examples

Basic example

var maxdiff_page = {
  type: 'maxdiff',
  alternatives: ['apple', 'orange', 'pear', 'banana'],
  labels: ['Most Preferred', 'Least Preferred'],
  preamble: '<p> Please select your <b>most preferred</b> and <b>least preferred</b> fruits. </p>'
};