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.
The probability of a Type I error is equal to the significance level , and the probability of rejecting the null hypothesis when it is in fact false (a correct decision) is equal to 1 - . To minimize the probability of Type I error, the significance level is generally chosen to be small.