TS ISO 7870-6

TS ISO 7870-6 addresses EWMA control charts for monitoring the process mean, with particular attention to detecting small and moderate shifts earlier than many traditional charts. In statistical process control, the method uses an exponentially weighted moving average of past observations or subgroup averages, so the chart reflects both current performance and accumulated history of the process.

What EWMA means in process monitoring

EWMA stands for exponentially weighted moving average. Conceptually, it gives more influence to recent data and progressively less to older data. That makes the chart especially useful when a process is drifting gradually or changing slightly over time. In general technical terms, this is a smoothing and surveillance approach rather than a simple snapshot of the latest result, which is why it can be more sensitive to subtle mean shifts.

According to the document scope, EWMA charts are worthwhile when production rates are slow, when detecting a minor or moderate shift in the process mean is important, when sampling and inspection are complex or time-consuming, when testing is expensive, or where safety risks are involved. The standard also notes that EWMA charts can be applied to both variables and attributes data, so the same basic monitoring idea can be adapted to measured values as well as counted or classified outcomes.

Typical application context

• Useful where early detection of small mean shifts matters.
• Combines current observations with weighted historical data.
• Applicable to both variables data and attributes data.
• Particularly relevant when inspection or testing is costly or slow.