Answer
There is no control group
Work Step by Step
The experiment is uncontrolled, which means that there is no control group and thus the improvement might be due to the placebo effect instead of actual improvement.
A P-value of 0.048 would not be too large to be convincing at the 5% confidence level.
The response variable does not need to have an exact Normal distribution in the population, because the sample size of 37 is large and thus the central limit theorem tells us that the sampling distribution of the sample mean is approximately normal.
