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.
Independent and Dependent Samples (Jump to: Lecture | Video ) So far I've talked about one-sample methods, and two-sample methods. One-sample methods are things like the one sample z-test, one sample z-test for proportions, and one sample t-test. In these tests, one sample is being compared to the population. Now in two-sample methods, samples are being compared to other samples.