The phrase "a decrease in segregation for" is correct and usable in written English.
You can use it when discussing a reduction in segregation related to a specific group or context.
Example: "The study showed a decrease in segregation for minority students in urban schools over the past decade."
Alternatives: "a reduction in segregation for" or "a decline in segregation for".
Dr Catney's briefing for the Centre on the Dynamics of Ethnicity at Manchester university, reveals that the most ethnically diverse neighborhoods are in districts which have seen a decrease in segregation for the majority of ethnic minority groups.
Leicester, Birmingham, Manchester and Bradford, along with other large cities, have recorded a decrease in segregation for most ethnic groups and interestingly the data shows that rural areas and small cities and towns are becoming more ethnically mixed.
Dollis Hill in Brent and Plaistow North in Newham, for example are the most diverse electoral wards in England and Wales but are both in districts which have seen a decrease in segregation.
The shift in immigration, along with a decrease in segregation between ethic groups, has contributed significantly to the ethnically diverse composition of the city today.
Such segregation indices can also be used in a positive fashion, such as discerning which of two industries has smaller segregation (greater diversity) or whether a given industry has had a decrease in segregation (increase in diversity) over time.
Cutler and Glaeser (1997) reported that a decrease in segregation by one standard deviation (13%) would eliminate one-third of the black white differences in education and employment.
After harmonising time-series data on a consistent geographical basis a decrease in residential segregation is observed for most groups, with alterations on the index values that can be greater than the impact of changes over time.
Catney found that inner London has experienced a drop in segregation for most ethnic groups although a 3% increase in segregation by white British is also recorded.
There were 115 inmates placed in segregation for three to six months, 61 inmates for six months to a year and 12 inmates in segregation for over a year.
This would lead to a significant decrease in levels of social segregation, while also giving all schools a fairer chance of improving their performance.
