Answer:
So that you can collect the number of data that you need according to the optimization of costs using the most positive data from the past, I suggest you make a control chart which is done as follows:
They are made using a coordinate system, whose horizontal axis indicates the time the data is framed, while the vertical axis serves as a scale to transcribe the measurement made. Measurement points are joined by straight lines. To plot the control chart, set the limits plus / minus the previously set tolerance values for the process being measured.
1. Control chart for fraction of nonconforming units (p) - p is the percentage of nonconforming units found in the controlled sample.
2. Control chart for number of nonconforming units (np) - It is equivalent to the previous chart, but applicable only if all the samples are the same size (n). - np = number of nonconforming units.
3. Control chart of nonconformities per unit (u) - It is used when several independent nonconformities (defects) can appear in the same unit of product or service, examples: assembly of complex components such as televisions, computers or provision of services with multiple points of contact with the client. - u = number of nonconformities of a unit.
4. Chart of control of number of nonconformities (c) - It is equivalent to the previous chart, but applicable only if all the samples are of the same size (n). - This graph is also used when the nonconformities are dispersed in a more or less continuous flow of product. - c = number of nonconformities.