IN THE PRECEDING ARTICLES of this series, an attempt was made to indicate the kind of questions to be asked about the manner in which data are first collected, then summarized, and finally analyzed. We dealt with an example of a situation in which we wished to establish a simple fact—the quantity of a specific occurrence in a population. In pursuing this fact, we found we had to question many things: We had to question the specific source from which the information might be obtained, question what might constitute a manageable portion which we could examine, question the method by which our observation could be made, question the manner in which our observational results might be translated into precise and manipulatable symbols, and finally question whether the symbols we used constituted an accurate representation of our findings. We later saw that as we became involved in the comparison of observations