Statistical Quality Control

Statistical process control (SPC) is the application of statistical methods to the monitoring and control of a process to ensure that it operates at its full potential to produce conforming product. Under SPC, a process behaves predictably to produce as much conforming product as possible with the least possible waste. While SPC has been applied most frequently to controlling manufacturing lines, it applies equally well to any process with a measurable output. Key tools in SPC are control charts, a focus on continuous improvement and designed experiments.

Statistical Process Control may be broadly broken down into three sets of activities: understanding the process, understanding the causes of variation, and elimination of the sources of special cause variation.

In understanding a process, the process is typically mapped out and the process is monitored using control charts. Control charts are used to identify variation that may be due to special causes, and to free the user from concern over variation due to common causes. This is a continuous, ongoing activity. When a process is stable and does not trigger any of the detection rules for a control chart, a process capability analysis may also be performed to predict the ability of the current process to produce conforming (i.e. within specification) product in the future.

When excessive variation is identified by the control chart detection rules, or the process capability is found lacking, additional effort is exerted to determine causes of that variance. The tools used include Ishikawa diagrams, designed experiments and Pareto charts. Designed experiments are critical to this phase of SPC, as they are the only means of objectively quantifying the relative importance of the many potential causes of variation.

Once the causes of variation have been quantified, effort is spent in eliminating those causes that are both statistically and practically significant (i.e. a cause that has only a small but statistically significant effect may not be considered cost-effective to fix; however, a cause that is not statistically significant can never be considered practically significant). Generally, this includes development of standard work, error-proofing and training. Additional process changes may be required to reduce variation or align the process with the desired target, especially if there is a problem with process capability.

What is the Statistics

Definition of Statistics

The study of expression data can moreover be particular or plural. What it refers to the authority, "statistics" is outstanding, as in "Statistics is an art." What it refers to quantities (such as mean and median) intended from a pot of data, statistics is plural, as in "These study of statistics are ambiguous."

Statistical actions may shape the foundation of positivist way in social sciences such as sociology. There is also a regulation recognized as numerical statistics, which is worried with the imaginary source of the subject.

Scope of Statistics:

• The study of statistics is painstaking by some for a statistical science pertaining to the compilation, analysis, understanding or explanation, and arrangement of data, while others believe it to be a division of mathematics.
• Disturbed amid collecting and interpreting data. Because of its empirical extraction its center on applications, statistics is frequently measured to be a different geometric science rather than a division of mathematics.
• Statisticians are humanizing the quality of numbers through the intend of experiments and survey sampling. Statistics also provides tackle for forecast forecasting with data and statistical models. Statistics is appropriate for broad selection of educational disciplines, counting normal and community sciences, government, and business.

Statistical Methods:

• Experimental and observational studies.
• Levels of measurement.

There are 4 types of dimensions or levels of measurement or dimension scales apply in statistics.They are,

• Nominal,
• Ordinal,
• Interval, and
• Ratio.

Erosion Control Method

Erosion Control Methods

Some of the methods for controlling erosion includes:

1. BUFFER STRIP: It is one of the method in controlling erosion. Buffer strip is nothing but an area of land .These are used in permanent vegetation which helps to control air, soil, and water quality, and environmental problems, which deals with land that is used in agriculture. Buffer strips helps in filtering nutrients and pesticides .

fig shows buffer strip erosion control method

2 . CROP ROTATION : In this method of erosion control , there is practice of growing a series of different types of crops in the same area in sequential seasons. The reason behind this is to avoid the build up of germs and pests that usually occurs when we grow same type of crops continuously . Crop rotation helps in avoiding decrease in soil fertility.

3.CONTOUR PLOUGHING : this method of erosion control , it is also called as contour farming. Here they follow a elevation contour line for plowing .The lines formed slows the water flow during rainfall. This prevent soil erosion and allows the water to get absorbed into the soil. contour bunding used the similar technology where stones are kept around the contours of slopes.

Other Type of Erosion Control Method

4 . TERRACE : In this method of erosion control a terrace is designed. This design will control the flow of water .This method appear in the form of multiple terraces.

5 .PERENNNIAL PLANTS : The deep roots of perennial plant, will hold soil to prevent erosion, it also capture dissolved nitrogen before contaminating ground and surface water

6.COVER CROPS : The uses of this erosion control method are it manage soil fertility, maintains soil quality, water, removes weeds , controls pests diseases.

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