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+<!--
+title: "Single (or Simple) Exponential Smoothing (`ses`)"
+sidebar_label: "Single (or Simple) Exponential Smoothing (`ses`)"
+custom_edit_url: https://github.com/netdata/netdata/edit/master/src/web/api/queries/ses/README.md
+learn_status: "Published"
+learn_topic_type: "References"
+learn_rel_path: "Developers/Web/Api/Queries"
+-->
+
+# Single (or Simple) Exponential Smoothing (`ses`)
+
+> This query is also available as `ema` and `ewma`.
+
+An exponential moving average (`ema`), also known as an exponentially weighted moving average (`ewma`)
+is a first-order infinite impulse response filter that applies weighting factors which decrease
+exponentially. The weighting for each older datum decreases exponentially, never reaching zero.
+
+In simple terms, this is like an average value, but more recent values are given more weight.
+
+Netdata automatically adjusts the weight (`alpha`) based on the number of values processed,
+using the formula:
+
+```
+window = max(number of values, 15)
+alpha  = 2 / (window + 1)
+```
+
+You can change the fixed value `15` by setting in `netdata.conf`:
+
+```
+[web]
+   ses max window = 15
+```
+
+## how to use
+
+Use it in alerts like this:
+
+```
+ alarm: my_alert
+    on: my_chart
+lookup: ses -1m unaligned of my_dimension
+  warn: $this > 1000
+```
+
+`ses` does not change the units. For example, if the chart units is `requests/sec`, the exponential
+moving average will be again expressed in the same units. 
+
+It can also be used in APIs and badges as `&group=ses` in the URL.
+
+## Examples
+
+Examining last 1 minute `successful` web server responses:
+
+-   ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=min&after=-60&label=min)
+-   ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=average&after=-60&label=average&value_color=yellow)
+-   ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=ses&after=-60&label=single+exponential+smoothing&value_color=orange)
+-   ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=max&after=-60&label=max)
+
+## References
+
+-   <https://en.wikipedia.org/wiki/Moving_average#exponential-moving-average>
+-   <https://en.wikipedia.org/wiki/Exponential_smoothing>.
+
+