1. A causal effect of X on Y is defined as:

2.Non-fulfilment of the zero-mean assumption for the disturbance term leads to the problem of _____.

3. Suppose that we wanted to sum the 2007 returns on ten shares to calculate the return on a portfolio over that year. What method of calculating the individual stock returns would enable us to do this?

4. In a simple linear regression equation, if X increases by 3 :