To test the effectiveness of a job training program on the subsequent wages of workers, we specify the model log(wage) = β0 + β1train + β2educ + β3exper + u, 11 where train is a binary variable equal to unity if a worker participated in the program. think of the error term u as containing unobserved worker ability. if less able workers have a greater chance of being selected for the program, and you use an ols analysis, what can you say about the likelybias in the ols estimator of β1?

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among other factors, composers started writing dynamic markings in their scores because "new instruments allowed for more dynamic ranges and contrast."

dynamics allude to the loudness or softness of music. dynamics offer an approach to demonstrate articulation in sheet music. they to drive the enthusiastic substance of music through volume and force. maybe you could alter both the volume and the shading profundity on your screen at the same time. we can likewise think about the force side of elements as the quality of a note. a few notes are intended to be played delicately and gently, while others are intended to be played all the more firmly.  

some dynamics markings have a letter 'm,' which remains for mezzo, signifying 'medium.' so a mezzo piano unique stamping resembles this (mp) and intends to play medium calm, while a mezzo specialty dynamic resembles this (mf) and intends to play medium loud.