What is the purpose of having effective size?

Topic: A Proven Effect
In Unit 6, you had the opportunity to give a town hall presentation to your community. As the director of the local public health department, stakeholders such as academicians, health professionals, state health department staff, representatives from affected communities, and representatives from nongovernmental organizations are looking to you to understand all aspects of the strategic planning process, as well as the results of the community needs assessment.
Using terms that anyone (academician or lay person with no statistical background) could understand, concisely answer the following questions:
How can you determine (prove) that the public health intervention or approach (applied to a specific community need/problem) you presented will have an effect?
What is the purpose of having effective size?
What is the definition of significance (significance testing)?
As you make decisions about the sustainability of the intervention presented, would affect size or significance be most important in your decision-making process? Why?

Include TWO academic references above 2017
NO CONSIDERATION FOR PLAGIARISM
APA FORMAT AND INDEX CITATION
PLEASE WRITE FROM PUBLIC HEALTH PERSPECTIVE