X

M

M × U

GDP

R&D

R-squared

r2_a

Model11

0.310^*

−0.012

0.064

0.692

0.645

Model12

0.335^***

0.026

0.175^***

0.947

0.936

Mode13

1.735^**

0.002

0.201^***

0.955

0.944