a health psychologist is interested in the possible effect of having to wait in a long (vs. short) line on attitudes toward the covid-19 vaccine. she conducts a survey at two local vaccination sites---one that always has long lines and another that always has short lines. in both cases, she approaches people waiting in line and asks them to fill out a brief survey assessing their attitudes toward the vaccine. afterward, she conducts an independent t-test and finds that people in the longer line had more negative attitudes toward the vaccine than did people in the shorter line.