Question

A natural experiment is a chance occurrence that mimics a randomized controlled trial. In order to analyze causal effects from natural experiments, economists make use of a statistical method known as instrumental variables, in which one variable from a natural experiment is used as an instrument for a particular independent variable of interest. Assume the independent variable of interest is x1 and the dependent variable in a regression is y. Which of the following represent necessary characteristics of a suitable instrument?
a. The instrument has at least 200 observations
b. The instrument is correlated with
c. The instrument has a conditional mean of zero
d. The instrument does not directly influence y, except through

Answer 1

Answer: b. The instrument is correlated with x1.

d. The instrument does not directly influence y, except through x1.

Explanation:

Based on the information given in the question, the necessary characteristics of a suitable instrument include:

• The instrument is correlated with x1.

• The instrument does not directly influence y, except through x1.

Some of the criteria for an instrument variable are the fact that it should have a causal effect on independent variable and also the dependent variable isn't directly affected except through the independent variable which is x1 in this scenario.

Therefore, the correct option are B and D.