A public goods dilemma is a situation in which the whole group can benefit if some give something toward the common good but others can profit from "free-riding."

Suppose you took a self-esteem inventory every Monday of the semester, and you found that your self-esteem scores varied across the semester. In particular, your total self-esteem scores were lowest during Midterm and Finals weeks. Which of the following explanations for this observation is MOST plausible?

A) ?The measure must not have undergone the necessary standardization process. B) ?The measure lacks reliability because different scores were observed over time. C) ?Personality traits are theoretically consistent over time, so this may not be a valid measure. D) ?Test norms are necessary in order to determine whether this trend is unique.

What can occur when a measure is too easy or obvious, leading to scores all being at the maximum level for that variable?

A. floor effect B. range effect C. experimenter effect D. ceiling effect