Apoc.math.regr calculations

[raghad_baiad]

Hello Neo4j knowledgable community,

I have a question regarding one of the apoc math functions, namely apoc.math.regr I have been using it to compute the linear regression estimators (slope, intercept) and the goodness-of-fit measure (R-squared). However, I noticed there is a huge difference between what is resultant out of this function and what is computed manually and using other tools adopting the least square approach. Therefore, I would appreciate your advice in figuring out/understanding what is used in the computation using the apoc regr function

[michael_hunger]

I think we just use apache.commons.math there, feel free to have a look at the source

github.com

neo4j-contrib/neo4j-apoc-procedures/blob/4.2/core/src/main/java/apoc/math/Regression.java#L34

    
      

          
    public double slope;
          

          
    public Output(double r2, double avgX, double avgY, double slope) {
          
        this.r2 = r2;
          
        this.avgX = avgX;
          
        this.avgY = avgY;
          
        this.slope = slope;
          
    }
          
}
          

          
@Procedure(name = "apoc.math.regr", mode = Mode.READ)
          
@Description("apoc.math.regr(label, propertyY, propertyX) - It calculates the coefficient " +
          
        "of determination (R-squared) for the values of propertyY and propertyX in the " +
          
        "provided label")
          
public Stream<Output> regr(@Name("label") String label,
          
                           @Name("propertyY") String y, @Name("propertyX") String x) {
          

          
    SimpleRegression regr = new SimpleRegression(false);
          
    double regrAvgX = 0;
          
    double regrAvgY = 0;
          
    int count = 0;
      
    
  

and the tests.