In cusum charts when all the data points are on the target except for 1 or 2 of them that occur 1point above/ below the target. So even if its showing its significant. Is it statistically significant? Yes or No. And why?

Thanks

In cusum charts when all the data points are on the target except for 1 or 2 of them that occur 1point above/ below the target. So even if its showing its significant. Is it statistically significant? Yes or No. And why?

Thanks

I should point out that if you are referring to "target" as related to a specification, specifications have no bearing on whether or not something is statistically significant. There is a description of a "target" in Acheson Duncan's Quality Control and Industrial Statistics for a single sided Cusum. But just exceeding the target is not statisically significant even in this scheme.

In the two sided CUSUM chart, a special "mask" is made. If one or more points fall outside of the limits of the "mask", then you have a statistically significant trend.