Kajsa Yang-Hansen is an assistant professor at the Department of Education at Gothenburg University who has researched the subject in depth.
She believes that one of the main underlying reasons for the fall in standards is the increase in segregation and inequality in the Swedish school system.
"It's mainly because of school segregation. Immigrant children have relatively lower inspiration in schools and at home. If you are in a classroom or a school where a large proportion of children are from well off homes, you will have positive inspiration," she told Radio Sweden.
The assistant professor also believed that the fall in standards was a resource question with better teachers choosing schools in more well off areas.
"It's a lot easier to teach children with a higher motivation and better attitude to school," Kajsa Yang-Hansen said.