Dr. Fielding is interested in the stratification system in the United States and how it is perpetuated through time. Fielding decides to examine the experiences of minority students who seek college counseling in high school. He interviews minority students in four high schools to learn whether their personal experiences tell him something about stratification in the United States. After interviewing the minority students, Fielding interviews nonminority students, school administrators, guidance counselors, teachers, parents, and social workers at the same four high schools. Fielding is probably using a/an approach.