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.
The independent variable is the variable that is different between the groups compared: all the members of one group will have the same level of the independent variable, a second group will have a different level of that same variable, and the same for a 3rd or 4th group, if present. is the independent variable and Y is the dependent variable-the outcome, and Z is the type of subjects represented. A simple example would be: The effects of tomatoes on risk of prostate cancer in Scandinavian men.