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.
Wearing colors has long been a way for gang members to show solidarity, but the FBI says gang members are indeed shying away from displaying identifiers. Often the only time colors and other identifiers are now displayed is at gang functions and funerals, according to the FBI's 2013 National Gang report. While gangs are showing their colors less, they have given police another way to identify them â their use of Facebook, Twitter and other social media sites.