Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_18268826_1 ( directed_by VARCHAR, us_viewers__million_ VARCHAR )

### Question ###
Who directed the episode seen by 3.93 million people in the US?

### Accurate SQL ###

SELECT directed_by FROM table_18268826_1 WHERE us_viewers__million_ = "3.93"