Question

1. Research shows that people from Asian descent are on average shorter and lighter than people from non-Asian ethnicity. Besides, people of Asian descent are also thought to weigh less for a given height. To test this hypothesis, you collect height and weight of 400 Asian students and 810 non-Asian students at your university. A regression of the weight on a constant, height, and a binary variable, which takes a value of one for Asian students and is zero otherwise, yields the following result:

Student weight= -229.21-6.36 Asian+558 Height, R2=0.50

where student weight is measured in Kilograms and height is measured in inches.

1.A Interpret the results (i.e., coefficients and R2). Does it make sense to have a negative intercept?

Answer 1

Interpretation of the coefficients:

If the Height is kept constant, the weight of an asian student is 6.36 kilograms less than a non-asian student of the same height.

If the ethnicity is kept same, the weight of a student increases by 5.58 kilograms for every inch increase of height.

The value of R-square as 0.5 implies that 50% of the variation in the dependent variable (i.e. student's weight) is explained by the ethnicity of the student and the height of the student.