Getting Statistics for Numeric Fields in Amazon CloudSearch
Amazon CloudSearch can return the following statistics for facetenabled numeric fields:

count
–The number of documents that contain a value in the specified field. 
max
–The maximum value found in the specified field. 
mean
–The average of the values found in the specified field. 
min
–The minimum value found in the specified field. 
missing
–The number of documents that do not contain a value in the specified field. 
stddev
–A measure to quantify the amount of deviation, or variation, in the field values. A low standard deviation indicates that the values across all documents are close to the mean. A high standard deviation indicates that the values are spread out over a large range. The standard deviation is calculated by taking the square root of the variance, which is the average of the squared differences from the mean. 
sum
–The sum of the field values across all documents. 
sumOfSquares
–The sum of all field values squared.
To get statistics for a field you use the stats.FIELD
parameter.
FIELD
is the name of a facetenabled numeric field. You specify an
empty JSON object, stats.FIELD={}
, to get all of the available statistics
for the specified field. (The stats.FIELD
parameter does not support any
options; you must pass an empty JSON object.) You can request statistics for multiple
fields in the same request.
You can get statistics only for facetenabled numeric fields: date
,
datearray
, double
, doublearray
,
int
, or intarray
. Note that only the count
,
max
, min
, and missing
statistics are returned
for date
and datearray
fields. For more information about
enabling a field to return facets, see configure indexing options.
For example, to search for star and get statistics for the year field, specify the following:
search?q=star&stats.year={}