The standard score of a raw score x is. where: The absolute value of z represents the distance between the raw score and the population mean in units of the standard deviation. z is negative when the raw score is below the mean, positive when above. A key point is that calculating z requires the population mean and the population standard deviation, not the sample mean or sample deviation.
The definition of a siren is a wailing sound made by passing air through a rotating disc, or a beautiful woman who uses sex to attract men, or a mythical female creature that lures men into the sea. 1  An example of a siren is the sound from a police car as it moves through traffic.
noun. 1. alert, warning, signal, alarm It sounds like an air raid siren. 2. seductress, vamp (informal), femme fatale (French), witch, charmer, temptress, Lorelei, Circe She's a voluptuous siren with a husky voice.