Composite decking is increasingly popular, as it requires little maintenance. Options include polyethylene (with an average cost per square foot of $7.82), polypropylene (average cost per square foot, $8.68) and polyvinyl chloride or PVC (average cost per square foot, $7.50 hollow core, $9.48 solid core.) Pros. Composite materials are very durable, and won't splinter or rot.
Two-sample t-tests for a difference in mean involve independent samples or unpaired samples. Paired t-tests are a form of blocking, and have greater power than unpaired tests when the paired units are similar with respect to noise factors that are independent of membership in the two groups being compared.
Stats: Dependent Means. There are two possible cases when testing two population means, the dependent case and the independent case. Most books treat the independent case first, but I'm putting the dependent case first because it follows immediately from the test for a single population mean in the previous chapter. The Mean of the Difference: The idea with the dependent case is to create a new variable, D, which is the difference between the paired values. You will then be testing the mean of this new variable. Here are some steps to help you accomplish the hypothesis testing. Write down the original claim in simple terms.