A normative statement carries judgment. Normative statements are opinions. They are subjective statements. For example, globalization inflicts economic harm to a country is an opinion.
Since they are opinions, they cannot be proven or disproven. Economists tend to stay away from normative statements.
A positive statement, on the other hand, is a factual statement. They can be tested or proven. These are objective statements.
The easiest way to discern normative statements from positive statements is to whether the statement is a fact or opinion.