README.md

In klausfrieler/BDT: R Implementation of the Beat Drop Alignment Test

Beat Drop Alignment Test (BDT)

The BDT is an adaptive test of beat perception ability.

Citation

When using the BDT in your own research, you can cite the original BDT research paper that is yet to be written.

We also advise mentioning the software versions you used, in particular the versions of the BDT, psychTestR, and psychTestRCAT packages. You can find these version numbers from R by running the following commands:

library(BDT)
library(psychTestR)
library(psychTestRCAT)
if (!require(devtools)) install.packages("devtools")
x <- devtools::session_info()
x$packages[x$packages$package %in% c("BDT", "psychTestR", "psychTestRCAT"), ]

Acknowledgements

Installation instructions (local use)

1. If you don't have R installed, install it from here: https://cloud.r-project.org/

2. Open R.

3. Install the ‘devtools’ package with the following command:

install.packages('devtools')

1. Install the BDT:

devtools::install_github('klausfrieler/BDT')

Usage

Quick demo

You can demo the melodic discrimination test at the R console, as follows:

# Load the BDT package
library(BDT)

# Run a demo test, with feedback as you progress through the test,
# and not saving your data
BDT_demo()

# Run a demo test, skipping the training phase, and only asking 5 questions
BDT_demo(num_items = 5, take_training = FALSE)

Testing a participant

The BDT_standalone() function is designed for real data collection. In particular, the participant doesn't receive feedback during this version.

# Load the BDT package
library(BDT)

# Run the test as if for a participant, using default settings,
# saving data, and with a custom admin password
BDT_standalone(admin_password = "put-your-password-here")

You will need to enter a participant ID for each participant. This will be stored along with their results.

Each time you test a new participant, rerun the BDT_standalone() function, and a new participation session will begin.

You can retrieve your data by starting up a participation session, entering the admin panel using your admin password, and downloading your data. For more details on the psychTestR interface, see http://psychtestr.com/.

The BDT currently supports English (EN) and German (DE). If you would like to add a new language to this list, please contact us. You can select one of these languages by passing a language code as an argument to BDT_standalone(), e.g. BDT_standalone(languages = "DE"), or alternatively by passing it as a URL parameter to the test browser, eg. http://127.0.0.1:4412/?language=DE (note that the p_id argument must be empty). Please note that the demo version of the test (BDT_demo) currently only supports English.

Results

The main output from the BDT is an ability score, corresponding to the ability estimate for the participant. It is computed from the underlying item response model and ranges approximately from -4 to +4. A secondary output is an ability_sem score, corresponding to the standard error of measurement for the ability estimate; again, it is computed from the underlying IRT model. For most applications you would only use the ability value, unless using a statistical analysis technique that allows you to specify measurement error explicitly. For more information about item response theory, see the Wikipedia article.

psychTestR provides several ways of retrieving test results (see http://psychtestr.com/). Most are accessed through the test's admin panel.

• If you are just interested in the participants' final scores, the easiest solution is usually to download the results in CSV format from the admin panel.
• If you are interested in trial-by-trial results, you can run the command compile_trial_by_trial_results() from the R console (having loaded the BDT package using library(BDT)). Type ?compile_trial_by_trial_results() for more details.
• If you want still more detail, you can examine the individual RDS output files using readRDS(). Detailed results are stored as the 'metadata' attribute for the ability field. You can access it something like this:

x <- readRDS("output/results/id=1&p_id=german_test&save_id=1&pilot=false&complete=true.rds")
attr(x$BDT$ability, "metadata")

Installation instructions (Shiny Server)

1. Complete the installation instructions described under 'Local use'.
2. If not already installed, install Shiny Server Open Source: https://www.rstudio.com/products/shiny/download-server/
3. Navigate to the Shiny Server app directory.

cd /srv/shiny-server

1. Make a folder to contain your new Shiny app. The name of this folder will correspond to the URL.

sudo mkdir BDT

1. Make a text file in this folder called app.R specifying the R code to run the app.

2. To open the text editor: sudo nano BDT/app.R

3. Write the following in the text file:

library(BDT)
BDT_standalone(admin_password = "put-your-password-here")

• Save the file (CTRL-O).

• Change the permissions of your app directory so that psychTestR can write its temporary files there.

sudo chown -R shiny cabat

where shiny is the username for the Shiny process user (this is the usual default).

1. Navigate to your new shiny app, with a URL that looks like this: http://my-web-page.org:3838/cabat

Usage notes

• The BDT runs in your web browser.
• By default, audio files are hosted online on our servers. The test therefore requires internet connectivity.

Implementation notes

klausfrieler/BDT documentation built on April 5, 2024, 12:18 a.m.