Syntax for using the dbms_stats.gather_index_stats procedure

How to analyze an index using dbms_stats:

BEGIN
  SYS.DBMS_STATS.GATHER_INDEX_STATS (
     OwnName           => 'SCOTT'
    ,IndName           => 'STATUS_IDX_1'
    ,Estimate_Percent  => DBMS_STATS.AUTO_SAMPLE_SIZE
    ,Degree            => DBMS_STATS.DEFAULT_DEGREE 
    ,No_Invalidate     => DBMS_STATS.AUTO_INVALIDATE);
END;
/

Official documentation here