Comparison of Efficiency and Sensitively between (Three Sigma, Six Sigma and Median Absolute Deviation) by using Xbar Control Chart

The main objective of any productivity operation is to get high quality materials and conform to the
specifications so as to meet consumer desires. The quality is
a principle in which some may think it is new, but it is as old
as human, because the man was still in a permanent search
for a good thing, and paying attention to the quality
.Quality has great care in the industrialized developed
countries being of economies exporter seek to control the
foreign markets, scale estimators are very important in
many statistical applications. The most common of scale
estimators is the sample standard deviation. Standard
deviation is non-robust to slight deviations from normality.
The present study introduces the Comparison between
another robust measure of dispersion namely Modified
(Three Sigma, Six Sigma and Median Absolute Deviation)
based on Shewhart mean control chart. When we compare
robust methods, six sigma method have better property
than the other robust methods, because control chart
based on six sigma have the smallest control interval and
also have the most number of out of control points.