You are trying to model average test score across different elementary schools as a function of average class size to determine whether smaller classrooms are more beneficial to students' performance but you forgot to include poverty rate in the school district in your model (that is poverty rate is now part of the error term). Would you expect the coefficient for class room size (measured by the number of students per teacher) to be biased? If yes, discuss directionality of the bias. Bias= corr(StudentsPerTeacher, TestScore)*corr(PovertyRate, StudentsPerTeacher)="+" Bias=corr(TestScore, PovertyRate)*corr(StudentsPerTeacher, PovertyRate)="_" Bias= corr(PovertyRate, TestScore)*corr(StudentsPerTeacher, PovertyRate)="+" Bias=0 Bias= corr(TestScore, StudentsPerTeacher)*corr(StudentsPerTeacher, PovertyRate)=*-"