Read and analyze the paper of Spalding et al., 2012 by answering the following P

Read and analyze the paper of Spalding et al., 2012 by answering the following Problem Based Learning Questions:
(1) What are the research problem, state of art or background used (why the topic is important?) and the main objectives of the paper (scientific hypothesis of the study or theory used).
(2) What is the scientific approach, the methodology, methods or sampling strategy if any used to reach these objectives (how the topic is studied?).
(3) Describe or present the main results.
(4) What are the main conclusions, interests, and progress beyond the state of art.
please dont use AI (artificial intelligence), as it is illegal, and pelergisem will be checked.