13.4 Detecting Specification Errors Tests of Specification Errors (Test the control variable Xai is an irrelevant varible. t test Misspecified model Y=B1+B2×2+B3X31+B441+;(13.14)13.4 Detecting Specification Errors: Tests of Specification Errors (1)Test the control variable X4i is an irrelevant varible: t test Misspecified model: Yi=B1+B2X2i+B3X3i +B4X4i +μi (13.14）