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.
The sound of a civil defense siren. (file). ( 1 original sense) (Greek mythology) One of a group of nymphs who lured mariners to their death on the rocks. 2  A device, either mechanical or electronic, that makes a piercingly loud sound as an alarm or signal, or the sound from such a device.