Cluster sampling refers to a type of sampling method . With cluster sampling, the researcher divides the population into separate groups, called clusters. Then, a simple random sample of clusters is selected from the population. The researcher conducts his analysis on data from the sampled clusters.
If you are running around an actual football field (100 yds x 50 yds) a mile would be 5.9 laps (1 mi = 1760 yds/300 = 5.86667). A standard racetrack around a football field should be 440 yds, so 4 laps should be a mile there (1760/440 = 4).
A football field is marked with yard lines every 5 yards starting at either end zone line. If a player crosses either of the sidelines with the ball, he is considered to be out of bounds and the next play begins where the ball went out of bounds.