When more people walk along a waterfront, the perception that it is a safe area increases. When a waterfront area is perceived as safe, people are more likely to walk there. A researcher estimates the effect of safety perceptions on walking. Her study is an example of ignoring

Biological and chemical weapons share which of the following characteristics?

a. They are regarded as a "poor man's atomic bomb". b. They can cause widespread injury and death. c. They are prohibited by international law. d. All these are characteristics of biological and chemical weapons.

In statistical notation the letter n refers to the __________________.

a. Standard deviation b. Variance c. Sample size d. Sampling error