Zero is in the interval, so do not reject the null. There is no evidence that one program is better than the other.

is greater than , so reject the null. This is evidence that one program is better at reducing mile times than the other.

Zero is not in the interval, so reject the null. This is evidence that one program is significantly better at reducing mile times.

The confidence interval is large, so one program is clearly better at reducing mile times than the other.

The mean improvement of second is too small to matter, so reject the null. There is no evidence that one program is better at reducing miles times.