Simulation experiments may be used to maintain the of an experiment yet still retain the of research conducted in the real world.

internal validity; external validity

Explanation:

The simulation experiment or a computer experiment is performed to verify the correctness of any program or operation and to evaluate the performance  of the proposed project.

It is mainly used for the process analysis as well as for the process optimization of the experiment. Doing a simulation experiment maintains the internal validity of the experiment. It also maintains the external validity of the research that is conducted in the real world.

vertical merger is the term used for the joining of two or more firms involved in different stages of producing the same good or services.

explanation:

1. seasonal

2. frictional unenployment

3. the number of the labor force multiplied by 100 and then subtract the number of unemployed.

4. 4%

5. an increase in prices