Where can I read more about this? I suspect the deviation would most largely result from the parameters of a given test itself. Redefining the test content, su

Where can I read more about this? I suspect the deviation would most largely result from the parameters of a given test itself. Redefining the test content, subject matter, test environments, conditions, and/or other factors may grow or shrink that gap. If that is so there is cause for research to determine why certain test factors are preferential and if removing such preferential factors does/does not result in higher quality student performance.