otreeutils 0.3.1

A package with common oTree utilities

otreeutils

November 2016, Markus Konrad [e-mail] / Berlin Social Science Center

A package with common oTree utilities

This repository contains the package otreeutils. It features a set of common helper / utility functions and classes often needed when developing experiments with oTree. So far, this covers the following use cases:

• Displaying and validating understanding questions
• Easier creation of surveys
• Displaying warnings to participants when a timeout occurs on a page (no automatic form submission after timeout)

Compatibility note: This package has been tested with oTree v1.0 through v1.4 and is also compatible with oTree v2.0.

This package is available on PyPI and can be installed via pip install otreeutils.

Examples

The repository contains two example apps which show the respective features and how they can be used in own experiments:

• otreeutils_example1 -- Understanding questions and timeout warnings
• otreeutils_example2 -- Surveys

Installation and setup

In order to use otreeutils in your experiment implementation, you only need to do two things:

1. Either install the package from PyPI via pip (pip install otreeutils) or download/clone this github repository and copy the otreeutils folder to your oTree experiment directory
2. Edit your settings.py so that you add "otreeutils" to your INSTALLED_APPS list

API overview

It's best to have a look at the (documented) examples to see how to use the API.

otreeutils.pages module

ExtendedPage class

A common page extension to oTree's default Page class. All other page classes in otreeutils extend this class. Allows to define timeout warnings, a page title and provides a template variable debug with which you can toggle debug code in your templates / JavaScript parts.

The template variable debug is toggled using an additional APPS_DEBUG variable in settings.py. See the settings.py of this repository. This is quite useful for example in order to fill in the correct questions on a page with understanding questions automatically in a debug session (so that it is easier to click through the pages).

UnderstandingQuestionsPage class

Base class to implement understanding questions. A participant must complete all questions in order to proceed. You can display hints. Use it as follows:

from otreeutils.pages import UnderstandingQuestionsPage

class SomeUnderstandingQuestions(UnderstandingQuestionsPage):
    page_title = 'Set a page title'
    questions = [
        {
            'question': 'What is π?',
            'options': [1.2345, 3.14159],
            'correct': 3.14159,
            'hint': 'You can have a look at Wikipedia!'   # this is optional
        },
        # ...
    ]

By default, the performance of the participant is not recorded, but you can optionally provide a form_model and set a field in form_field_n_wrong_attempts which defines in which field the number of wrong attempts is written.

If you set APPS_DEBUG to True, the correct answers will already be filled in order to skip swiftly through pages during development.

otreeutils.surveys module

create_player_model_for_survey function

This function allows to dynamically create a Player model class for a survey. It can be used as follows in models.py.

At first you define your questions per page, for example like this:

from otreeutils.surveys import create_player_model_for_survey


GENDER_CHOICES = (
    ('female', 'Female'),
    ('male', 'Male'),
    ('no_answer', 'Prefer not to answer'),
)


SURVEY_DEFINITIONS = (
    {
        'page_title': 'Survey Questions - Page 1',
        'survey_fields': [
            ('q1_a', {   # field name (which will also end up in your "Player" class and hence in your output data)
                'text': 'How old are you?',   # survey question
                'field': models.PositiveIntegerField(min=18, max=100),  # the same as in normal oTree model field definitions
            }),
            ('q1_b', {
                'text': 'Please tell us your gender.',
                'field': models.CharField(choices=GENDER_CHOICES),
            }),
            # ... more questions
        ]
    },
    # ... more pages

Now you dynamically create the Player class by passing the name of the module for which it will be created (should be the models module of your app) and the survey definitions:

Player = create_player_model_for_survey('otreeutils_example2.models', SURVEY_DEFINITIONS)

The attributes (model fields, etc.) will be automatically created. When you run otree resetdb, you will see that the fields q1_a, q1_b, etc. will be generated in the database.

SurveyPage class

You can then create the survey pages which will contain the questions for the respective pages as defined before in SURVEY_DEFINITIONS:

Please note: Unfortunately, it was not possible for me to create the page classes dynamically, so you have to define them manually here. At least the overhead is minimal, because you don't need to define any additional attributes.

# (in views.py)

from otreeutils.surveys import SurveyPage, setup_survey_pages


class SurveyPage1(SurveyPage):
    pass
class SurveyPage2(SurveyPage):
    pass
# more pages ...

# Create a list of survey pages.
# The order is important! The survey questions are taken in the same order
# from the SURVEY_DEFINITIONS in models.py

survey_pages = [
    SurveyPage1,
    SurveyPage2,
    # more pages ...
]

setup_survey_pages function

Now all survey pages need to be set up. The Player class will be passed to all survey pages and the questions for each page will be set according to their order.

# Common setup for all pages (will set the questions per page)
setup_survey_pages(models.Player, survey_pages)

Finally, we can set the page_sequence in order to use our survey pages:

page_sequence = [
    SurveyIntro,  # define some pages that come before the survey
    # ...
]

# add the survey pages to the page sequence list
page_sequence.extend(survey_pages)

# we could add more pages after the survey here
# ...

License

Apache License 2.0. See LICENSE file.