BOSTON -- State education officials plan to bring in outside researchers to analyze this year's MCAS test results for any "unintended consequences" of a question on the 2016 novel "The Underground Railroad" that sparked student concerns and calls for the test as a whole to be disregarded.

Five groups -- the Mass. Teachers Association, the Boston Teachers Union, the American Federation of Teachers Massachusetts, the Massachusetts Education Justice Alliance and the New England Area Conference of the NAACP -- this month called on the Department of Elementary and Secondary Education to invalidate this year's English language arts exam, saying students were shaken by a question that asked them to write a journal entry from the perspective of a character the groups said is "openly racist and betrays slaves trying to escape."

The teachers' unions and advocacy groups issued their press release on April 3, and state education officials later that day publicly released a letter from Riley that he had sent three days earlier suggesting that educators no longer administer the question.

At a Board of Elementary and Secondary Education meeting in Newton Tuesday, Education Commissioner Jeff Riley offered more details about the situation around the test question.

Riley said Laura Perille, the interim superintendent in Boston, contacted the department on Friday, March 29 after students at "several" city schools expressed concerns. He said he reviewed the question himself the next morning and, "out of an abundance of caution," made the decision to pull the question so it would not count for students who had already taken the test. Students who had yet to take the test were instructed to skip the question.

"As the head of this organization, I accept responsibility and apologize for this oversight," Riley said. "We are continuing to review all the information related to this issue to see how we can improve the process in the future."

Riley said the state has a "thorough process" to develop and screen questions, but this question "got past us." He said he plans to meet with the students who raised concerns "to commend them for their efforts to speak out about this particular item."

Juan Cofield, president of the NAACP's New England Area Conference, addressed the board during its public comment period, reiterating the call to nullify the question.

"You've got the option to throw the test out, to not require it as a criteria for graduation, and I hope that you will do that," he said.

Cofield said the question "had a serious impact for some students," putting them "in a position of doing less well than they might otherwise have done."

Riley said the question was reviewed not only by an assessment development committee but by a "bias and sensitivity committee made up of a diverse group of educators," who accepted it on three separate occasions, including after a field test with students last year.

"Even after removing this question, test developers have assured me that the test remains sound, valid and reliable in terms of assessing students' performance in English language arts," he said. "However, internally, we will do a thorough analysis of the results of this test as we do every year, and in addition to the [department]-led analysis, we are commissioning external research from Stanford University to run an independent analysis to make sure there are no unintended consequences."