This chapter describes some important features of any epidemiological study. Whatever the matter being investigated, it is likely that any palaeoepidemiological study is a variant on one of the three types; a cross-sectional study; a ranking study; or a case-control study. Collecting data will almost certainly occupy the most time in an epidemiological study, sometimes even surpassing the amount of time spent applying for and waiting for the award of a grant. In osteoarthritis the degree of joint space narrowing and the presence of marginal osteophyte are used for a radiographic diagnosis that would almost certainly result in a higher prevalence being recorded than when the palaeoepidemiological operational definition is used. The prime object of any study is an outcome variable of some sort, frequently a disease or condition such as tuberculosis, spondylolysis, or Paget’s disease. The chapter also presents some closing thoughts on the key concepts discussed in the preceding chapters of this book.