# jspsych-survey-likert plugin

The survey-likert plugin displays a set of questions with Likert scale responses. The subject responds by selecting a radio button.

## Parameters

This table lists the parameters associated with this plugin. 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
----------|------|---------------|------------
questions | array | *undefined* | Each array element a string. The strings are the prompts/questions that will be associated with a slider.
labels | array |  *undefined* | Each array element is an array of strings. The innermost arrays contain a set of labels to display for an individual question. If you want to use blank responses and only label the end points or some subset of the options, just insert a blank string for the unlabeled responses.
preamble | string | empty string | HTML formatted string to display at the top of the page above all the questions.
required | boolean | false | Makes answering questions required.
button_label | string | 'Button label' | Label of the button.

## Data Generated

In addition to the [default data collected by all plugins](overview#datacollectedbyplugins), this plugin collects the following data for each trial.

Name | Type | Value
-----|------|------
responses | JSON string | A string in JSON format containing the response for each question. The encoded object will have a separate variable for the response to each question, with the first question in the trial being recorded in `Q0`, the second in `Q1`, and so on. The responses are recorded as integers, representing the position of the slider on the scale.
rt | numeric | The response time in milliseconds for the subject to make a response. The time is measured from when the questions first appear on the screen until the subject's response.

## Examples

#### Basic example with multiple questions on a page.

```javascript
// defining groups of questions that will go together.
var page_1_questions = ["I like vegetables.", "I hate eggs."];

// defining two different response scales that can be used.
var scale_1 = ["Strongly Disagree", "Disagree", "Neutral", "Agree", "Strongly Agree"];

var likert_page = {
    type: 'survey-likert',
    questions: ["I like vegetables.", "I like fruit."],
    labels: [scale_1, scale_1], // need one scale for every question on a page
};
```