1 The total project cost for a Trex deck ranges between $1,500 and $2,200 for a 250sf deck. 2  Trex Select of basic quality averages approximately $7/sf.  Trex Enhance of higher quality is approximately $8/sf.
When the hypothesized value is zero then there is a simple relationship between hypothesis testing and confidence intervals: If the interval contains zero then the null hypothesis cannot be rejected at the stated level of confidence. If the interval does not contain zero then the null hypothesis can be rejected.
If the P value is exactly 0.05, then either the upper or lower limit of the 95% confidence interval will be at the null value. Similarly, the 99% confidence interval will exclude the null if and only if the test of significance yields a P value of less than 0.01.