According to the sixth principle of SPC a frequency distribution will be deviating from normal distribution, only in the presence of any assignable cause. A frequency distribution is a tally of measurements that shows the number of times the measurement is included int he tally. From this frequency distribution we can see if there are only chance causes present in the process of any assignable causes are acting. If there Read More …

# Tag: Statistical Process Control

## Fifth Principle of SPC – shape of the distribution

The Fifth Principle of SPC states that it is possible to determine the shape of the distribution form the measurements of any process. We can learn abut what the process is doing, against what we want the process to do. For this we need to measure the output of the process with the design specifications.the process can be altered if we donot like the comparison, especially if we see a variation. Read More …

## Fourth Principle of SPC – the shape is like a bell

Fourth Principle of SPC is logical extension of the third principle which is covered in my last post. In which it was said that most measurements will be clustered around the middle. In Fact it was proved by statisticians that we can make failry accurate predictions of the percentage measurements in the various sections of the frequency distribution curve. Frequency curve with normal distribution You can see this graph Most Read More …

## Third Principle of SPC – Things Vary in a pattern

The Third Principle of SPC is extension of the second one. In the last post on Second Principle of SPC, I mentioned that we notice a Feature if the measurements of the output are analysed. If we want to see the pattern, all we need to do is plot the individual data points or the measures taken onto a tally form. we will see definite pattern begin to form after several measurements Read More …

## Second Principle of SPC – Variation can be measured

We have already discussed about the same thing done by us giving different output in the first principle of SPC. The second principle is based on the first principle and states that the variation in the process can be measured. Some Variation is always inherent to our job and this is acceptable to some extent so far as the variation is within the Tolerance. However, the Variation tends to increase Read More …

## Basic Principles of Statistical Process Control

The six principles below are the Basic Principles of Statistical Process Control (SPC). These can be clearly understood using Frequency Distributions. The principles are listed below. The explanation is linked to each sentence No two things are exactly alike Variation in a product or process can be measured Things Vary according to a definite pattern Whenever things of the same kind are measured, a large group of the measurements will tend to Read More …

## Control Charts

Control Charts is a running record of the process performance. It is a recod of results of periodic sampling inspections. A chart becomes a control chart when it has control limits based on inherent process variation. Process control limits are boundaries on a control chart within which the process can operate to a standard. These limits are based on natural variation of the process without the influence of assignable causes. Read More …