Physical Traces

Read the following research description and answer the questions that follow.

Description:

A student researcher has come up with what she believes is an ingenious unobtrusive measure of student anxiety before exams. Specifically, she finds out that large introductory sections of courses in the social sciences (e.g., psychology, political science) and natural sciences (e.g., biology, chemistry) at her university make use of standardized tests scored by a computer. Students in these classes are given small, No. 2 pencils prior to each exam. Students return the pencils by dropping them in a box on the way out of the classroom. The researcher suggests that biting or chewing on a pencil is a sign of anxiety. Her hypothesis is that students enrolled in natural science courses (mainly pre-med students) are more anxious about exams than those students taking courses in the social sciences. Because at the time of the first exam the pencils are new and have not been previously used by students, the student researcher decides to collect data after the first exam in each of these large classes. She obtains permission from the instructors to examine the pencils following the initial exams in these courses. She then counts the number of pencils with teeth marks. Her results appear to support her hypothesis. A greater proportion of pencils in the natural science classes have teeth marks than do pencils in the social science classes.

1		What is the student’s operational definition of anxiety?
2		Did the student employ a natural use trace or a controlled use trace? Be sure to explain why you selected the measure that you did.
3		Illustrate how selective deposit might operate in this situation to produce a spurious relationship between the type of class (natural science or social science) and the unobtrusive measure of anxiety.