Allowing customisation of limits

[Peter Li]

Feature request to allow setting of limits across the entire SPC chart, through two approaches:

1. Setting limits based on a limited sample of the SPC chart. This may be implemented as a new field which flags the point for inclusion in the calculation of limits. This will enable multiple scenarios:
   1. If there are 36 data points in the SPC, and we only want to use the first 18 points to calculate the limits.
   2. To allow for the exclusion of outlier points in the limit calculation, or temporary process changes that we don't want to include.
2. Setting your own custom limits by bringing in your own mean and sigma. This will allows users to monitor their process based on the expected value and variance.

[Matthew Callus]

In response to the suggestion of being able to add a baseline period, below is how this works with the Making Data Count tools:

A baseline period can be set for the initial points of the SPC chart, from which the mean and process limits are calculated and this is extended beyond (whereas with a recalculation, new mean and process limits are calculated from the post-baseline data).

In our Excel tool, this has to be for the first 12-20 points, but this restriction doesn't need to be implemented. As long as there are enough data points to calculate the mean and process limits from.

In our SQL tool, I added the ability to define the baseline period as either a set date (the last date point) or a set number of points.

In our Excel tool, it is not possible to add a recalculation after a baseline period but that is just a limitation of the tool. I added this to the SQL tool, as demonstrated here:

In our Excel tool, the baseline period is shown with the same line as the rest (i.e. dashed, which I know can be customised in the custom visual). For the SQL tool, I made this a solid line by default in the PBI output to help make clear where the baseline period ends. Therefore, it would be great if the baseline can have its own line to customise.