2 added 85 characters in body edited Jan 23 '15 at 0:22 Glen_b♦ 220k2323 gold badges433433 silver badges785785 bronze badges Rejecting a null is the same thing as achieving significance. If you understand "how to use confidence intervals to reject a null hypothesis", you've already done the other thing. In short, if the interval for $$\mu_x-\mu_y$$ doesn't include zero, your reject the null; equivalently you have achieved significance, thereby concluding $$\mu_x > \mu_y$$ Rejecting a null is the same thing as achieving significance. If you understand "how to use confidence intervals to reject a null hypothesis", you've already done the other thing. In short, if the interval for $$\mu_x-\mu_y$$ doesn't include zero, your reject the null; equivalently you have achieved significance, thereby concluding $$\mu_x > \mu_y$$ Rejecting a null is the same thing as achieving significance. If you understand "how to use confidence intervals to reject a null hypothesis", you've already done the other thing. In short, if the interval for $$\mu_x-\mu_y$$ doesn't include zero, your reject the null; equivalently you have achieved significance, thereby concluding $$\mu_x > \mu_y$$ 1 answered Mar 24 '13 at 21:25 Glen_b♦ 220k2323 gold badges433433 silver badges785785 bronze badges Rejecting a null is the same thing as achieving significance. If you understand "how to use confidence intervals to reject a null hypothesis", you've already done the other thing. In short, if the interval for $$\mu_x-\mu_y$$ doesn't include zero, your reject the null; equivalently you have achieved significance, thereby concluding $$\mu_x > \mu_y$$