I'm quite new to this field, so excuse me for any misuse of jargon or anything else. My project is about integrating GWAS data with scRNA-seq. In this project, I'm using MAGMA software, you can look the manual in this website https://ctg.cncr.nl/software/MAGMA/doc/manual_v1.07.pdf . In the gene-level analysis section of the manual, it said that it uses linear regression model, to see whether a particular gene-set is associated to the phenotype of interest. But, I just can't understand how can they reach to that conclusion using linear regression. I guess it will be easier for me to understand it if someone can elaborate in more details each term in the regression model, since in the manual it's just to brief for me to understand. And for side question, why do they use linear model instead of any other model? I would like to thank you in advance.