I have a question on interpreting coefficients in a regression model. To be specific, the regression model is as given below:
y= continuous dependent variable x1= independent variable all values are positive (min=0) x2= independent variable all values are negative (max=0) Z = Normalized variable with values between (0,1)
Given this set up, how would we interpret
a) positive and significant coefficient b1 b) negative and significant coefficient b4 c) What can we say about a joint test of b1+b4=0
x1 and x2 represent the same variable X (continous) and the goal is to allow for different slopes when X is positive and negative. Any help is much appreciated.
The question is motivated from the regression output in the following paper
Greve, Henrich R. "A behavioral theory of R&D expenditures and innovations: Evidence from shipbuilding." Academy of management journal 46.6 (2003): 685-702.