Taking the 2PL as an example, we illustrate how to use the Shiny app below.
In the first step, the server end (e.g., test administer, school board) can be launched by running the Shiny app (runserver()) with the interface shown below:
Then, the client-end Shiny app can be initialized (runclient()).
When the client first launches, it will automatically connect to the localhost port 8000 as default.
If the server is deployed on another computer, type the server’s IP address and port (which will be displayed on the server’s interface), then click “reconnect”. The screenshots of the user interface are shown below.
Then, the client should choose a file to upload to the local Shiny app to do local calculations, without sending it to the server. The file should be a csv file, with either binary or graded response, and all clients should share the same number of items, and the same maximum score in each item (if the answers are polytomous), otherwise, there will be an error message suggesting to check the datasets of all clients.
After all the clients upload their data, the server should click “start” to begin the federated estimates process and after the model converges, the client should click “receive result”. The server will display all item parameters and the client will display all item parameters and individual ability estimates.
The clients will also display bar plots of the ability estimates.
