# jspsych-survey-multi-choice plugin

The survey-multi-choice plugin displays a set of questions with multiple choice response fields. The subject selects a single answer.

## 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
----------|------|---------------|------------
questions | array | *undefined* | An array of objects, each object represents a question that appears on the screen. Each object contains a prompt, options, required, and horizontal parameter that will be applied to the question. See examples below for further clarification.`prompt`: Type string, default value is *undefined*. The string is prompt/question that will be associated with a group of options (radio buttons). All questions will get presented on the same page (trial).`options`: Type array, defualt value is *undefined*. An array of strings. The array contains a set of options to display for an individual question.`required`: Type boolean, default value is null. The boolean value indicates if a question is required('true') or not ('false'), using the HTML5 `required` attribute. If this parameter is undefined, the question will be optional. `horizontal`:Type boolean, default value is false. If true, then the question is centered and the options are displayed horizontally. `name`: Name of the question. Used for storing data. If left undefined then default names (`Q0`, `Q1`, `...`) will be used for the questions.
randomize_question_order | boolean | `false` | If true, the display order of `questions` is randomly determined at the start of the trial. In the data object, `Q0` will still refer to the first question in the array, regardless of where it was presented visually.
preamble | string | empty string | HTML formatted string to display at the top of the page above all the questions.
button_label | string |  'Continue' | Label of the button.
autocomplete | boolean | false | This determines whether or not all of the input elements on the page should allow autocomplete. Setting this to true will enable autocomplete or auto-fill for the form.

## Data Generated

In addition to the [default data collected by all plugins](overview#data-collected-by-plugins), 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 the name of the option label. If the `name` parameter is defined for the question, then the response will use the value of `name` as the key for the response in the `responses` object.
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.
question_order | JSON string | A string in JSON format containing an array with the order of questions. For example `[2,0,1]` would indicate that the first question was `trial.questions[2]` (the third item in the `questions` parameter), the second question was `trial.questions[0]`, and the final question was `trial.questions[1]`.

## Examples

```javascript
var page_1_options = ["Strongly Disagree", "Disagree", "Neutral", "Agree", "Strongly Agree"];
var page_2_options = ["Strongly Disagree", "Disagree", "Somewhat Disagree", "Neural", "Somewhat Agree", "Agree", "Strongly Agree"];

var multi_choice_block = {
  type: 'survey-multi-choice',
  questions: [
    {prompt: "I like vegetables", name: 'Vegetables', options: page_1_options, required:true}, 
    {prompt: "I like fruit", name: 'Fruit', options: page_2_options, required: false}
  ],
};

var multi_choice_block_horizontal = {
  type: 'survey-multi-choice',
  questions: [
    {prompt: "I like vegetables", options: page_1_options, required: true, horizontal: true,}, 
    {prompt: "I like fruit", options: page_2_options, required: false, horizontal: true}
  ],
};
```