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.
1 Harpy-A half-bird, half-woman creature of Greek mythology, portrayed often as a woman with a body of a bird and the head of a human. 2  Siren-A creature of Greek mythology with a bird body and a human's head. 3  Sirin-Half-bird, half-human creature with the head and chest of a woman from Russian folklore.