Generalizability Theory Tool


G_String_VI is the most recent 'incarnation' of G_String, a computer program for analyzing psychometric performance tests based on Generalizability Theory. It is typically employed to optimize competence exams. G_String was originally developed for the Windows platform at McMaster University in 2006 and gradually evolved since.

G_String_VI was redesigned from scratch in 2020. It is improved in three ways:

  • It runs on Windows, MacOS and Linux.
  • It accommodates a significantly larger range of experimental designs than earlier versions.
  • It incorporates a sophisticated logging system to facilitate trouble shooting.
  • Its upper limit for the number of data points that can be handled has been essentially eliminated.
  • It can now also generate synthetic data sets of any size for practice and experimentation.

The G_String line of programs has been designed and coded by Ralph Bloch as a retirement project in collaboration with Geoff Norman.

 

Installation

G_String_VI runs on all major OS platforms for desktop and laptop computers. It does not run on tablets and smart phones. For all platforms the program is contained in a software package called 'G_String_VI.jar. Because G_String_VI.jar is not digitally signed, the actual installation differs slightly from operating system to operating system. Once the program has been installed initially, no further efforts are required for future updates.

          To download G_String_VI.jar file, click here

          To download the G_String_VI manual, click here.

But before you download G_String_VI.jar, make sure that you have installed the Java Runtime JRE 8 on your computer.

Then select your operating system:

 

  1. If necessary, install Oracle Java 8 Run-Time Environment (RTE).
  2. Create a new directory 'G_String_VI' in a suitable location of your file system.
  3. Adjust User Account level (UAC) to 'Notify me only when applications try to make changes (do not dim my desktop)'.
  4. Download the software package 'G_String_VI.jar' (see above) and copy it from your system's 'Downloads' directory into 'G_String_VI'. Make it executable. Allow when asked.
  5. Start G_String_VI. jar by double clicking on it. Create a 'work' subdirectory in 'G_String_VI' and select it. (Setup > Set Working Directory).
  6. Reset UAC to 'Notify me only when applications try to make changes (default)'.





 

 

  1. If necessary, install Oracle Java 8 Run-Time Environment (RTE).
  2. Create a new directory 'G_String_VI' in a suitable location of your file system.
  3. Apple Icon > Security & Privacy > Padlock > Sign In > Unlock > Allow Application from Anywhere.
  4. Download the software package 'G_String_VI.jar' (see above) and copy it from your system's 'Downloads' directory into 'G_String_VI'. Make it executable. Allow when asked.
  5. Start G_String_VI. jar by double clicking on it. Create a 'work' subdirectory in 'G_String_VI' and select it. (Setup > Set Working Directory).
  6. Reset Application Download permission to 'from Mac App Store.




 

 

  1. If necessary, install Oracle Java 8 Run-Time Environment (RTE).
  2. Create a new directory 'G_String_VI' in a suitable location of your file system.
  3. Download the software package 'G_String_VI.jar' (see above) and copy it from your system's 'Downloads' directory into 'G_String_VI'. Make it executable. Allow when asked.
  4. Start G_String_VI. jar by double clicking on it. Create a 'work' subdirectory in 'G_String_VI' and select it. (Setup > Set Working Directory).



 

Trouble Shooting

The request for volunteer beta-testers, unfortunately, was not very successful. In the end, only one brave soul ran a dataset. Consequently the new version of G_String may still harbor some unrealized bugs. However, most unexpected returns from G_String_VI will probably be due to faulty parameter specifications or problems with data formats.

 

If you get a mysterious error message, or G_String_VI does not complete its calculations, first review your input and the data file. If that doesn't seem to explain the cause of the problem, send a short description of your design and a copy of the data file to G_String's author ralph@papaworx.com.

If instructed, set the 'Log Level' to 'FINEST' (Setup > Log Level) and repeat the sequence that didn't give the expected results. After exiting G_String_VI you find the 'G_String_VI.log' file in your computer's Home directory. Send it together with the design description and data file to 'ralph@papaworx.com'

 

For the very curious, it might actually be instructive to examine 'G_String_VI.log' in a text editor. But in any case, you can expect a response to your help request within a few days.

If all else fails, and you can't resolve the problem on your own, we can always schedule an interactive session via Google Hangouts.

 

G-School

Below is a list of linked videos with further explanation on Generalizability Theory and using G_String_VI:

G-Theory Introduction

 

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