# Mrs. Rhodes Math Class 2016

## Mean and Standard Deviation

Standard Deviation (SD) is the measure of spread of the numbers in a set of data from its mean value. Also called as SD, Standard Deviations symbol σ (sigma). This can also be said as a measure of variability or volatility in the given set of data.

## Empirical Rule

A statistical rule stating that for a normal distribution, almost all data will fall within three standard deviation of the mean.

## Control Chart

Statistical tool used in quality control to analyze and understand process variables, determine process capabilities, and to monitor effects of the variables on the difference between target and actual performance. Control charts indicate upper and lower control limits, and often include a central (average) line, to help detect trend of plotted values.

## Out of control Signals

Out of control signals is when dots that make up lines go out side the dotted lines on the chart.

## z scores- calculating

A Z-score, also known as a standard score, is a measure for how far a data point is above or below the population mean, expressed in standard deviations. It is calculated as the difference between a data point (x) and the population mean (μ), divided by the population standard deviation (σ)