A setup against its null

Over 1 Apr–31 Oct 2026 the pullback rules produced 36 trades with mean $-0.557R$ and standard deviation $0.576R$. Random entries with the same exits produced a mean of $-0.325R$ with standard error $0.046R$. (a) Compute the $z$-statistic for the difference between the setup's mean and the null's mean, treating the two estimates as independent. (b) Give two reasons why the true uncertainty of the setup's mean is larger than $0.576/\sqrt{36}$. (c) For the Coal India trade (position ₹2,11,765.46, costs ₹522.77, stop distance ₹21.80 on a ₹462.37 entry), compute the friction per trade in R from costs plus 0.1% slippage on each side. (d) Recompute (c) for a stop at 2.5 ATR (ATR ₹13.67), assuming costs stay the same fraction of notional. What does this say about tight stops?