A multi-value metrics aggregation that computes stats over numeric values extracted from the aggregated documents. These values can be extracted either from specific numeric fields in the documents, or be generated by a provided script.

The extended_stats aggregations is an extended version of the stats aggregation, where additional metrics are added such as sum_of_squares, variance and std_deviation.

Assuming the data consists of documents representing exams grades (between 0 and 100) of students

{
    "aggs" : {
        "grades_stats" : { "extended_stats" : { "field" : "grade" } }
    }
}

The above aggregation computes the grades statistics over all documents. The aggregation type is extended_stats and the field setting defines the numeric field of the documents the stats will be computed on. The above will return the following:

{
    ...

    "aggregations": {
        "grades_stats": {
            "count": 6,
            "min": 72,
            "max": 117.6,
            "avg": 94.2,
            "sum": 565.2,
            "sum_of_squares": 54551.51999999999,
            "variance": 218.2799999999976,
            "std_deviation": 14.774302013969987
        }
    }
}

The name of the aggregation (grades_stats above) also serves as the key by which the aggreagtion result can be retrieved from the returned response.

{
    ...,

    "aggs" : {
        "grades_stats" : { "extended_stats" : { "script" : "doc['grade'].value" } }
    }
}

{
    "aggs" : {
        ...

        "aggs" : {
            "grades_stats" : {
                "extended_stats" : {
                    "field" : "grade",
                    "script" : "_value * correction",
                    "params" : {
                        "correction" : 1.2
                    }
                }
            }
        }
    }
}