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.
The Thin Blue Line is a symbol used by law enforcement, originating in the United Kingdom but now prevalent in the United States and Canada to commemorate fallen and to show support for the living law enforcement officers and to symbolize the relationship of law enforcement in the community as the protectors of fellow civilians from criminal ...