A mining company is interested in the pH levels of soil before and after mining is completed. The pH levels from 15 areas of the mining land are taken before mining begins. At the conclusion of mining, the land is restored and another set of pH readings were taken on the same 15 grids. Is this data paired or independent data?
A random sample of 8 new SUV's and 8 mid-size cars are tested for front impact resistance. The amounts of damage (in hundreds of dollars) to the vehicles when crashed at 20 mph head on into a stationary barrier are recorded. Investigators want to know if the SUV's are sturdier and thus suffer less damage. Is this paired data or independent data?