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.
Instructor: Orin Davis. T-tests are used to compare two means to assess whether they are from the same population. T-tests presume that both groups are normally distributed and have relatively equal variances. The t-statistic is distributed on a curve that is based on the number of degrees of freedom (df).