Final answer:
Sally is collecting ordinal data by studying the grade ranking of the senior class, which allows for the ordering of students based on their GPA without specific quantitative differences.
Step-by-step explanation:
Sally is gathering ordinal data while studying the grade ranking of the senior class. This type of data deals with ranking or ordering of items and is common when looking at positions within a structured group like a class ranking. In the context given, the rank of each student is an ordinal number indicating their position in the hierarchy from the highest to the lowest grade point average (GPA).
Ordinal data is typically used when the order is important but the difference between the values cannot be determined mathematically. It contrasts with nominal data, where information is categorized without a specific order, and interval/ratio data, which involve measurements and quantitative differences.
For example, if a statistics professor collects information about the classification of students as freshmen, sophomores, juniors, or seniors, and summarizes it in a pie chart, this shows nominal data because it categorizes students without any order or ranking.