This is a great place to start. When using ground beef to make hamburger patties, be sure to select the right meat. Lean ground beef like ground sirloin or the 7% fat meat will tend to make dry burgers.
Changes in lifestyles, nutrition, and ethnic composition of populations lead to changes in the distribution of body dimensions (e.g. the obesity epidemic), and require regular updating of anthropometric data collections.
In statistics we tend use the 'hat' notation to imply a statistic. We designate P to represent the proportion in the population. Because P is unknown and unknowable we use Phat to designate the proportion in the sample. Suppose 30 out of 100 people in my sample support Trump. Phat = 30/100 = .30. P = unknown and unknowable.