Hey everyone, welcome to this lecture control charts selection for continuous data. control chart selection is a vast topic in itself. I have divided this topic into two lectures. In the first lecture, we will discuss selection of control charts for continuous data. In the next, we will discuss for discrete data. Let's begin.
Imagine a situation where all floats are manufactured only in one size. Whether you're thin or plumb, the market supply for clothes will only be of one sighs Oh man, I cannot imagine such a situation. similar to this, there is not one control chart that fits all situations. There are different types of situations and different control charts designed for those situations. These different conditions are best described as situations involving continuous And those involving discrete data. An important point to note, if you are new to the concept of continuous and discrete data, please review the reference reading material that I have attached in the resources section of this lecture.
It will give you a clear idea of what is continuous as well as discrete data. Let us now talk about those situations involving continuous data. I will share three examples. Example one, a team is tracking cycle time, it is measured in days it takes to process claims. The team randomly selects one completed claim each day and plotted the time it took to complete that one claim. Example to a team is tracking cycle time.
It is measured in days it takes to process claims. They randomly select five completed claims each day and plot the average cycle time and example three Process owner is monitoring call and it is measured in minutes and seconds. Each day the average length of all calls received is plotted the call center receives over 100 calls per day. There are two critical observations in these three examples. Observation one, the metric being tracked. In example, one and two is cycle time.
And that in example three is the column and these matrix are continuous in nature. And observation two is that, In example one, the team is plotting one completed claim each day. An example to the team is plotting five completed claims each day and an example three, the team is plotting length of hundred calls each day. These data points of one, five and hundred are nothing but the subgroup sizes in each of the examples. What is a subgroup, a subgroup is a group of units produced under the same set of conditions. subgroups are meant to represent a snapshot of the process, they represent a sample of a homogeneous population at large.
So, coming back to the examples and control chart selection to select the right control chart, you will first identify if the data that you are plotting is continuous or discrete. If it is continuous, you will then identify whether the subgroup size is equal to one greater than one and less than or equal to eight or is it greater than eight. If the subgroup size is equal to one, you will use an IMR or individuals moving range chart if the subgroup size is greater than one and less than or equal to eight You will use an x bar R or mean and range chart. Lastly, if the subgroup size is greater than eight, you will use an x bar s or mean and standard deviations chart. Let me now put this information in the form of a chart. This is how it looks.
And this is how you select control charts for continuous data. Thank you for attending. See you in the next one.