A writer in a medical journal says: "An uncontrolled experiment in 37 women found a significantly improved mean clinical symptom score after treatment. Methodologic flaws make it difficult to interpret the results of this study." The writer is skeptical about the significant improvement because
(a) there is no control group, so the improvement might be due to the placebo effect or to the fact that many medical conditions improve over time.
(b) the P-value given was P= 0.048, which is too large to be convincing.
(c) the response variable might not have an exactly Normal distribution in the population.