Calculation From Raw Score
The standard score of a raw score x is
where:
- μ is the mean of the population;
- σ is the standard deviation of the population.
The quantity 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. It requires knowing the population parameters, not the statistics of a sample drawn from the population of interest. But knowing the true standard deviation of a population is often unrealistic except in cases such as standardized testing, where the entire population is measured. In cases where it is impossible to measure every member of a population, the standard deviation may be estimated using a random sample.
Read more about this topic: Standard Score
Famous quotes containing the words calculation, raw and/or score:
“Common sense is the measure of the possible; it is composed of experience and prevision; it is calculation appled to life.”
—Henri-Frédéric Amiel (1821–1881)
“Our acceptance of an ontology is, I think, similar in principle to our acceptance of a scientific theory, say a system of physics; we adopt, at least insofar as we are reasonable, the simplest conceptual scheme into which the disordered fragments of raw experience can be fitted and arranged.”
—Willard Van Orman Quine (b. 1908)
“I have a Vision of the Future, chum.
The workers’ flats in fields of soya beans
Tower up like silver pencils, score on score.”
—Sir John Betjeman (1906–1984)