What does the term 'hirearchy of broader experiments' actually mean?

I am in my first year of a degree with OU and my tutor recently mentioned this term in relation to my end of module assignment...I think she is referring to broadening the information used from case studies and experiments and not getting so in depth with individual pieces of evidence...She has told me that I write in a very concise style so I think I can achieve this but I don't get exactly what this term means...