Running your experiment

Once you have created an experiment using either create-empirica-app or a git clone.

Installing the node modules

Whenever you first pull or clone an app from a repository, you need to run this command to install all the Node packages:

meteor npm install

Running the app locally

Run the app on your local machine with one command:


This can take a few minutes.

This will start the app that you can access as a participant: https:/localhost:3000/

You can access the admin panel here: https:/localhost:3000/admin

Log in with the username and password provided in the command line.

Loading the factors and treatments

Treatments and factors can also be entered manually via the admin panel.

Empirica also enables "experiment as code" by which experimental treatments and factors can stored in a .yaml file (e.g., factors.yaml).

To load factors and treatments from a .yaml file , go in the admin panel and:

  • click on the Configuration button

  • click on import

  • select the .yaml file you want to import the factors and treatments from

  • wait a few seconds for the factors and treatments to be imported

Testing the app

To run a game, create a new batch with the games of treatments you want to use and click start on the batch.

Open a player tab by going to https:/localhost:3000/ or clicking on open app.

The player that you open with https:/localhost:3000/ is cached on your browser. Whenever you start a game with this player, your local app will keep that information. To play again there are multiple things you can do:

  • Click on the Reset current session button in the top right to reset this player, and create a new game for this player to join.

  • Click on the New Player button in the top right to open a new tab with a different player (you will see tab with an id).

  • Go to the Players tab in the admin panel and retire players that have finished or cancelled.

The app will automatically ("hot") reload when save changes to the code.

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