# mean

(redirected from X-bar)
Also found in: Dictionary, Thesaurus, Medical, Legal, Encyclopedia.

## Mean

The expected value of a random variable. Arithmetic average of a sample.

## Arithmetic Mean Average

An average calculated by adding the value of the points in a data set and dividing the sum by the number of data points. For example, suppose one wishes to calculate the average income of a country with exactly five people in it, and their incomes are \$25,000, \$26,000, \$43,000, \$70,000, and \$72,000. It is calculated as:

(\$25,000 + \$26,000 + \$43,000 + \$70,000 + \$72,000) / 5 = \$47,200.

A limitation to the arithmetic mean average is that it can be overly affected by extremes in either direction. For example, if one of the five persons in the country earns \$100 billion per year, the arithmetic mean average income would be in the billions and would not accurately count the other four citizens. For this reason, many analysts use the median in conjunction with the arithmetic mean average. The arithmetic mean average is also called simply the mean.

## mean The average of a set of numbers.Contrast with median,which is the middle figure in a set of numbers,and mode,which is the value that appears most often in a set of numbers.

Example: A survey of home values in a neighborhood of nine houses obtained the following values:

The mean, or average, is the total of all values divided by 9, or \$143,044.The median is the middle number when the numbers are all arranged from highest to lowest,which would be house 5, or \$139,850.The mode is \$139,000,because it is the number that appears most often.

References in periodicals archive ?
Figure 3 depicts the keyed dimension format with a plotting grid and with the data entry table and R chart below the X-bar chart.
Duncan proposed an economic model for x-bar control charts in 1956.
Pratt (1953) notes the right skew in the moisture distribution but ignored it when using the range to establish control limits on the x-bar chart.
"Everything is real-time, with x-bar and R charts immediately available," Mr Parks says.
On-Line Analyst for quality control provides X-bar, R, and sigma charts and generates C, U, P, NP, moving-average/moving-range, and individual charts.
And like its mold line counterpart, the software also has the capability to chart and print X-bar and R charts to provide a history of sand quality with each order.
The software includes improved graphical interfaces for more operator-friendly use, improved data transfer utilities, automated network reporting capabilities and new programming features that include off-line adjustment of specification limits, a new X-bar and R SPC chart and barcode program changeover.
It will provide statistical analysis - including X-bar and R charts, moving-range charts, P charts, and other relevant formats - of the molding process in real time.
From its turning and milling work, machine operators logged SPC data and plotted their own X-bar, R, and capability charts by hand on color-keyed forms to ensure that processes ran within guidelines.
X-bar and R charts are plotted for any measured variable.
The most commonly used charts--and the ones you should start with--are the X (X-bar) and R charts.
Of these, the x-bar chart, r-chart, individual-x chart and moving-range chart are most frequently used in analysis for the reflow process.

Site: Follow: Share:
Open / Close