1 files changed, 64 insertions, 0 deletions
diff --git a/src/web/api/queries/median/README.md b/src/web/api/queries/median/README.md
new file mode 100644
index 000000000..e6f6c04e7
--- /dev/null
+++ b/src/web/api/queries/median/README.md
@@ -0,0 +1,64 @@
+<!--
+title: "Median"
+sidebar_label: "Median"
+description: "Use median in API queries and health entities to find the 'middle' value from a sample, eliminating any unwanted spikes in the returned metrics."
+custom_edit_url: https://github.com/netdata/netdata/edit/master/src/web/api/queries/median/README.md
+learn_status: "Published"
+learn_topic_type: "References"
+learn_rel_path: "Developers/Web/Api/Queries"
+-->
+
+# Median
+
+The median is the value separating the higher half from the lower half of a data sample
+(a population or a probability distribution). For a data set, it may be thought of as the
+"middle" value.
+
+`median` is not an accurate average. However, it eliminates all spikes, by sorting
+all the values in a period, and selecting the value in the middle of the sorted array.
+
+Netdata also supports `trimmed-median`, which trims a percentage of the smaller and bigger values prior to finding the
+median. The following `trimmed-median` functions are defined:
+
+- `trimmed-median1`
+- `trimmed-median2`
+- `trimmed-median3`
+- `trimmed-median5`
+- `trimmed-median10`
+- `trimmed-median15`
+- `trimmed-median20`
+- `trimmed-median25`
+
+The function `trimmed-median` is an alias for `trimmed-median5`.
+
+## how to use
+
+Use it in alerts like this:
+
+```
+ alarm: my_alert
+    on: my_chart
+lookup: median -1m unaligned of my_dimension
+  warn: $this > 1000
+```
+
+`median` does not change the units. For example, if the chart units is `requests/sec`, the result
+will be again expressed in the same units. 
+
+It can also be used in APIs and badges as `&group=median` in the URL. Additionally, a percentage may be given with
+`&group_options=` to trim all small and big values before finding the median.
+
+## 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)
+-   ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=median&after=-60&label=median&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/Median>.
+
+