In a study conducted in New Zealand, researchers Parkin et al. randomly assigned volunteers to wear either socks over their shoes (intervention) or their usual footwear (control) as they walked downhill on an inclined icy path. Researchers standing at the bottom of the inclined path would then rate how confident the participant appeared (“confident,” “cautious but did not hold onto supports,” or “held onto supports”) and how much time (seconds) the participant took to walk down the path.

a. Was this an experiment or an observational study?
b. Identify the variables recorded. For each variable, identify the type (categorical or quantitative) and role (explanatory or response).
c. Did the study involve randomness? If so, how: random sampling, or random assignment, or both?