Hi readers! Today we will discuss about Control Chart. A Control Chart consists of a central line and a pair of control limits, one on either sides, allocated above and below the central line.
Basic uses of Control Charts.
- It is used to determine whether a process is in a state of statistical control or out- of- control. It also shows the degree and nature of variation over time.
- Control charts are used to estimate the parameters (mean, variation) of a process. By knowing the parameters of a process, the output and the variability of the output can be predicted.
- Charts control charts are used to improve a process. Once a process is in control, efforts to produce process variability can begin. By reducing the variability of the process, the overall quality of the final product can be increased.
In above picture we can see that all points are lying in between in Upper and lower control limit. So, this control chart can be considered in to be in a controlled state.
Types of control chart.
Discrete Data – Data are said to be discrete when they take only a finite number of points that can be represented by non-negative integers. An example of discreate data is the number of defects in a sample.
Discrete data can be easily visualized and demonstrated using simple statistical methods such as bar charts, line charts or pie charts.
Some more example of Discrete data
- The number of participants who have attended the meeting.
- The number of customers who have brought the shirt online.
- The number of printers in each department.
Continuous data – Data are said to be continuous when they exist on an interval or on several intervals. An example of continuous data is the measurement of pH.
Some more examples of continuous data.
- Weight of car.
- Temperature of a freezer.
- Measurement of speed of wind on weekly basis.