TRUE OR FALSE QUESTIONS.

1. The existence of omitted variables that do not affect the dependent variable and are strongly correlated with the independent variable is one justification for using IV.
2. Suppose you are regressing an Individual's income on their years of education to identify the effect of education on income. Using an instrumental variable could be sensible in this context.
3. By randomizing treatment in an experiment, we can guarantee that omitted variables enjoy a strong correlation with the independent variable.
4. By randomizing treatment in an experiment, we can guarantee that omitted variables enjoy a negative correlation with the independent variable.
5. When we know there exist omitted variables that affect the dependent variable and are negatively correlated with the independent variable, causal inference becomes impossible
6. When we know there exist omitted variables that affect the dependent variable and are positively correlated with the independent variable, causal inference becomes impossible