The Educational Results Partnership Outperforming Look-a-Like Schools measure utilizes a statistical method called a linear regression which models the causal relationship between two variables. Once the relationship has been identified, supplying the value for one of the variables will allow a prediction of the other value.
The linear regression model creates the expectation for performance based on the percentage of a demographic group in the school population. Look-a-Like Schools are schools that have a similar percentage of the given demographic group.
The number displayed below is the difference between the expectation based on the linear regression model for the school and the school's actual performance. Positive numbers indicate that the school is outperforming look-a-like schools by the number of percentage points. Negative numbers indicate the school is underperforming look-a-like schools.