In order to determine if a finding from one study can be applied to other populations, it is necessary for researchers to variables, thus making it possible for other researchers to try to replicate the study.

Operationally define

Explanation:

Operational definable variable are those variables that can be defined in particular manner to which it can be used in a study or research for measurement .These variables tend to be defined by the researchers so that it can studied in specific way.

According to the question, researchers should use operationally define variable in the research to conclude about finding can be implied on other population or not by replication.

operationally define.

Explanation:

Reliability refers to how something is reliably calculated by a system. If the same result can be obtained accurately using the same methods in the same circumstances, the measurement shall be deemed correct. But it works with the principle of validity which refers to what degree the tests assess what they should be measuring. Therefore to increase the credibility of a research operationally defined variables increases its validity and reliability.

b) to encourage free trade

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer