We know that infants fall asleep easily when being gently rocked, but what would be the effect on adults? A 2019 study recruited a random sample of 18 healthy young adults to monitor their quality of sleep over two nights, assessed by the latency to deep sleep (measured in minutes, with shorter a latency being more beneficial). In random order, on one night the participants slept in a stationary bed and on the other night they slept in a bed that gently rocks. The published report states that, compared to a stationary night, continuous rocking shortened the latency to deep sleep, on average. 1. The Study is

a. An unscientific study using voluntary response or anecdotal data
b. cross sectional sample survey
c. a matched pair/ repeated measure experiment
d. a completely randomized experiment
e. a census (population data)
f. a case-control observational study
g. a longitudinal cohort study

2. Since the stated differences in latency were greater than chance variations, can we conclude that, in lab conditions, a gently rocking bed causes reduced latency to deep sleep, on average, among healthy young adults?

a. No, because sleep latency was observed and not imposed
b. No, because the difference wasn’t large
c. Yes, because the sleep condition was imposed randomly
d. No, because association isn’t causation
e. Yes, because the difference was large