A t-test can be used to account for the uncertainty in the sample variance when the sample size is small and the data are exactly normal. There is no universal constant at which the sample size is generally considered large enough to justify use of the plug-in test. Typical rules of thumb range from 20 to 50 samples.
Each symbol and color in the National Law Enforcement Explorers seal has special significance. 1  The circular form of the seal represents continuous existence. 2  The dominant blue field represents justice. 3  The inner circle contains a shield surmounted by an eagle.
California is the only state I'm aware of that has tried to standardize uniform colors by type of agency. Police departments generally wear dark blue, sheriff's departments wear tan (khaki) shirts over olive green trousers, and the highway patrol and a few other state-level law enforcement agencies wear tan uniforms. Some departments put a stripe or braid on the outside seam of the trouser legs.