Add anova documentation

docs/en/sql-reference/aggregate-functions/reference/analysis_of_variance.md

@@ -0,0 +1,44 @@
+---
+slug: /en/sql-reference/aggregate-functions/reference/analysis_of_variance
+sidebar_position: 6
+---
+
+# analysisOfVariance
+
+Provides a statistical test for one-way analysis of variance (ANOVA test). It is a test over several groups of normally distributed observations to find out whether all groups have the same mean or not. 
+
+**Syntax**
+
+```sql
+analysisOfVariance(val, group_no)
+```
+
+Aliases: `anova`
+
+**Parameters**
+- `val`: value. 
+- `group_no` : group number that `val` belongs to.
+
+:::note
+Groups are enumerated starting from 0 and there should be at least two groups to perform a test.
+Moreover there should be at least one group with the number of observations greater than one.
+:::
+
+**Returned value**
+
+- `(f_statistic, p_value)`. [Tuple](../../data-types/tuple.md)([Float64](../../data-types/float.md), [Float64](../../data-types/float.md))
+
+**Implementation details**
+
+
+**Example**
+
+Query:
+
+```sql
+```
+
+Result:
+
+```response
+```

docs/en/sql-reference/aggregate-functions/reference/index.md

@@ -37,6 +37,7 @@ Standard aggregate functions:
 
 ClickHouse-specific aggregate functions:
 
+- [analysisOfVariance](/docs/en/sql-reference/aggregate-functions/reference/analysis_of_variance.md)
 - [any](/docs/en/sql-reference/aggregate-functions/reference/any_respect_nulls.md)
 - [anyHeavy](/docs/en/sql-reference/aggregate-functions/reference/anyheavy.md)
 - [anyLast](/docs/en/sql-reference/aggregate-functions/reference/anylast.md)