# Is it possible to have 1e-15 p-value when difference is about 1 SD?

The question is about the 2nd data table from the article Symptom improvement in children with autism spectrum disorder following bumetanide administration is associated with decreased GABA/glutamate ratios, specifically first row — total score.

Authors show the result of $$37.27±4.0937.27±4.09$$ (score in some test) in control group vs $$34.51±3.3534.51±3.35$$ in the group who took the medicine.

In the same row it’s stated that p-value for that is $$3.46 × 10^{−15}3.46 × 10^{−15}$$ even though the difference between groups is only about 1 SD.

So the question is: Are results specifically from the first row statistically significant? I have very basic understanding of statistics, but it seems to me that 1 SD is insignificant. Why do they have such a low p-value? Is it an “artifact” because they just multiplied probabilities?

The p 3.46 × 10−15 is not about the difference between groups but about the time × group interaction. The difference between groups has the p = 0.0012, which is in the text in the section Bumetanide improves ASD symptoms, and this p-value is correct given the numbers they provided. You can check it by plunging them into some t-test calculator.